KNF Knife River Corporation

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Knife River is a people-first construction materials and contracting services company. We provide construction materials and contracting services to build safe roads, bridges, airport runways and other critical infrastructure needs that connect people with where they want to go and with the supplies they need. Knife River is one of the leading providers of crushed stone and sand and gravel in the United States and operates across 14 states. We conduct our operations through five reportable segments: Pacific, Northwest, Mountain, Central and Energy Services.

In the fourth quarter of 2023, we realigned our reportable segments to better support our operational strategies. As a result, a portion of the Pacific segment’s businesses are now reported under the Energy Services segment. In addition, the North Central and South operating regions have been aggregated into one reportable segment, Central. We also reallocated certain amounts to the operating segments that were previously reported within Corporate Services. All periods have been recast to conform with the revised presentation. See Note 14 for additional information.

Separation from MDU Resources

On May 31, 2023, MDU Resources completed the previously announced separation of Knife River through the distribution of approximately 90 percent of the outstanding shares of common stock, par value $.01 per share, of Knife River to the stockholders of record of MDU Resources as of the close of business on May 22, 2023. MDU Resources retained approximately 10 percent of the outstanding shares of Knife River common stock. The Distribution was structured as a pro rata distribution of one share of Knife River common stock for every four shares of MDU Resources common stock. In November 2023, MDU Resources disposed of all 5,656,621 retained shares of Knife River common stock in an underwritten public offering. As a result of the Distribution, Knife River is now an independent public company and its common stock is listed under the symbol “KNF” on the New York Stock Exchange.

All share and earnings per share information has been retroactively adjusted for all periods presented to reflect the Distribution.

The accompanying consolidated interim financial statements were prepared in accordance with accounting principles generally accepted in the United States of America ("GAAP") for interim financial information and with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X. Interim financial statements do not include all disclosures provided in annual financial statements and, accordingly, these financial statements should be read in conjunction with the Company's 2023 Annual Report on Form 10-K ("Annual Report"). The information is unaudited but includes adjustments that are, in the opinion of management, necessary for a fair presentation of the accompanying consolidated interim financial statements and are of a normal recurring nature.

Prior to the Separation, Knife River operated as a wholly owned subsidiary of Centennial Energy Holdings, Inc., a direct wholly owned subsidiary of MDU Resources and the direct parent company of Knife River prior to the spinoff ("Centennial") and an indirect, wholly owned subsidiary of MDU Resources and not as a stand-alone company. The accompanying consolidated financial statements and footnotes for the periods prior to the Separation were prepared on a "carve-out" basis using a legal entity approach in conformity with GAAP and were derived from the consolidated financial statements of MDU Resources as if Knife River operated on a stand-alone basis during these periods.

All revenues and costs, as well as assets and liabilities, directly associated with our business activities are included in the consolidated financial statements. In the periods prior to the Separation, the consolidated financial statements include expense allocations for certain functions provided by MDU Resources and Centennial, including, but not limited to, certain general corporate expenses related to senior management, legal, human resources, finance and accounting, treasury, information technology, communications, procurement, tax, insurance and other shared services. These general corporate expenses are included in the Consolidated Statements of Operations within selling, general and administrative expenses and other income. For the three and six months ended June 30, 2023, the amount allocated to Knife River was $4.7 million and $9.6 million, respectively, in selling, general and administrative expenses and $300,000 and $600,000, respectively, in other income. These items were allocated on the basis of direct usage when identifiable, with the remainder principally allocated on the basis of percent of total capital invested or other allocation methodologies that were considered to be a reasonable reflection of the utilization of the services provided to the benefits received, including the following: number of employees paid and stated as cost per check; number of employees served; weighted factor of travel, managed units, national account spending, equipment and fleet acquisitions; purchase order dollars spent and purchase order line count; number of payments, vouchers or unclaimed property reports; labor hours; time tracked; and projected workload. The allocations may not, however, reflect the expenses we would have incurred as a

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stand-alone company for the periods presented. These costs also may not be indicative of the expenses that we will incur in the future or would have incurred if we had obtained these services from a third party.

Management has also evaluated the impact of events occurring after June 30, 2024, up to the date of issuance of these consolidated interim financial statements on August 6, 2024, that would require recognition or disclosure in the Consolidated Financial Statements.

Principles of consolidation

For all periods, the consolidated financial statements were prepared in accordance with GAAP and include the accounts of Knife River and its wholly owned subsidiaries. All intercompany accounts and transactions between the businesses comprising Knife River have been eliminated in the accompanying audited consolidated financial statements.

Use of estimates

The preparation of financial statements in conformity with GAAP requires us to make estimates and assumptions that affect the reported amounts of assets and liabilities, and disclosure of contingent assets and liabilities, at the date of the consolidated financial statements, as well as the reported amounts of revenues and expenses during the reporting period. Estimates are used for items such as long-lived assets and goodwill; fair values of acquired assets and liabilities under the acquisition method of accounting; aggregate reserves; property depreciable lives; tax provisions; revenue recognized using the cost-to-cost measure of progress for contracts; expected credit losses; environmental and other loss contingencies; costs on contracting services contracts; actuarially determined benefit costs; asset retirement obligations; lease classification; present value of right-of-use assets and lease liabilities; and the valuation of stock-based compensation. These estimates are based on management’s best knowledge of current events, historical experience, actions that we may undertake in the future and on various other assumptions that are believed to be reasonable under the circumstances. As additional information becomes available, or actual amounts are determinable, the recorded estimates are revised. Consequently, operating results can be affected by revisions to prior accounting estimates.

Cash, cash equivalents and restricted cash

We consider all highly liquid investments with an original maturity of three months or less, when purchased, to be cash and cash equivalents. Restricted cash represents deposits held by our captive insurance company that is required by state insurance regulations to remain in the captive insurance company. Cash, cash equivalents and restricted cash on the Consolidated Balance Sheets is comprised of:

			June 30, 2024			June 30, 2023			December 31, 2023
			(In thousands)
Cash and cash equivalents			$	15,468		$	40,089		$	219,324
Restricted cash			41,701			28,400			42,996
Cash, cash equivalents and restricted cash			$	57,169		$	68,489		$	262,320

Seasonality of operations

Some of our operations are seasonal and revenues from, and certain expenses for, such operations may fluctuate significantly among quarterly periods, with lower activity in the winter months and higher activity in the summer months. Accordingly, the interim results for particular segments, and for Knife River as a whole, may not be indicative of results for the full fiscal year or other future periods.

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The following table provides a brief description of the accounting pronouncements applicable to Knife River and the potential impact on its consolidated financial statements and/or disclosures:

Standard			Description			Standard Effective Date			Impact on financial statements/disclosures
Recently issued Financial Accounting Standards Board (FASB) accounting standards updates ("ASU") not yet adopted
ASU 2023-07 - Improvements to Reportable Segment Disclosures			In November 2023, the FASB issued guidance on modifying the disclosure requirements to improve reportable segment disclosure requirements through enhanced disclosures about significant segment expenses. The guidance also expands the interim disclosure requirements. The guidance is to be applied on a retrospective basis to the financial statements and footnotes and early adoption is permitted.			Fiscal periods beginning after December 15, 2023 and interim periods beginning after December 31, 2024			The Company is currently evaluating the impact the guidance will have on its disclosures for the year ended December 31, 2024 and interim periods for fiscal year 2025.
ASU 2023-09 - Improvements to Income Tax Disclosures			In December 2023, the FASB issued guidance on modifying the disclosure requirements to increase transparency about income tax information through improvements to income tax disclosures primarily related to the rate reconciliation and income taxes paid information. The guidance is to be applied on a prospective basis to the financial statements and footnotes, however, retrospective adoption is also permitted. The guidance also permits early adoption.			Fiscal periods beginning after December 15, 2024			The Company is currently evaluating the impact the guidance will have on its disclosures for the year ended December 31, 2025.

Receivables consist primarily of trade and contract receivables for the sale of goods and services net of expected credit losses. A majority of our receivables are due in 30 days or less. The total balance of receivables past due 90 days or more was $7.4 million, $11.6 million and $16.7 million at June 30, 2024, June 30, 2023 and December 31, 2023, respectively. Receivables were as follows:

			June 30, 2024			June 30, 2023			December 31, 2023
			(In thousands)
Trade receivables			$	206,673		$	220,948		$	124,134
Contract receivables			188,120			173,318			112,037
Retention receivables			32,649			30,224			36,782
Receivables, gross			427,442			424,490			272,953
Less expected credit loss			4,501			5,870			6,168
Receivables, net			$	422,941		$	418,620		$	266,785

The Company's expected credit losses are determined through a review using historical credit loss experience; changes in asset specific characteristics; current conditions; and reasonable and supportable future forecasts, among other specific account data, and is performed at least quarterly. We develop and document our methodology to determine our allowance for expected credit losses. Risk characteristics used by management may include customer mix, knowledge of customers and general economic conditions of the various local economies, among others. Specific account balances are written off when management determines the amounts to be uncollectible. Management has reviewed the balance reserved through the allowance for expected credit losses and believes it is reasonable.

Details of the Company's expected credit losses were as follows:

			Pacific			Northwest			Mountain			Central			Energy Services			Total
			(In thousands)
As of December 31, 2023			$	2,053		$	1,004		$	2,293		$	718		$	100		$	6,168
Current expected credit loss provision			177			(223)			(47)			87			—			(6)
Less write-offs charged against the allowance			(53)			133			2			3			—			85
At March 31, 2024			$	2,283		$	648		$	2,244		$	802		$	100		$	6,077
Current expected credit loss provision			25			79			27			151			1			283
Less write-offs charged against the allowance			513			11			1,122			212			1			1,859
At June 30, 2024			$	1,795		$	716		$	1,149		$	741		$	100		$	4,501

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			Pacific			Northwest			Mountain			Central			Energy Services			Total
			(In thousands)
As of December 31, 2022			$	1,945		$	1,253		$	1,278		$	901		$	100		$	5,477
Current expected credit loss provision			45			313			164			(90)			—			432
Less write-offs charged against the allowance			1			68			18			—			—			87
At March 31, 2023			$	1,989		$	1,498		$	1,424		$	811		$	100		$	5,822
Current expected credit loss provision			8			74			631			(131)			1			583
Less write-offs charged against the allowance			17			512			3			2			1			535
At June 30, 2023			$	1,980		$	1,060		$	2,052		$	678		$	100		$	5,870

Inventories on the Consolidated Balance Sheets were as follows:

			June 30, 2024			June 30, 2023			December 31, 2023
			(In thousands)
Finished products			$	245,983		$	227,683		$	225,319
Raw materials			100,029			104,689			61,776
Supplies and parts			39,366			42,005			32,528
Total			$	385,378		$	374,377		$	319,623

Inventories are valued at the lower of cost or net realizable value using the average cost method. Inventories include production costs incurred as part of our aggregate mining activities. These inventoriable production costs include all mining and processing costs associated with the production of aggregates. Stripping costs incurred during the production phase, which represent costs of removing overburden and waste materials to access mineral deposits, are a component of inventoriable production costs.

Basic net income per share is computed by dividing net income by the weighted average number of shares of common stock outstanding during the applicable period. Diluted net income per share is computed by dividing net income by the total of the weighted average number of shares of common stock outstanding during the applicable period, plus the effect of non-vested performance shares and restricted stock units. Weighted average common shares outstanding is comprised of issued shares of 57,043,841 less shares held in treasury of 431,136. Basic and diluted net income per share are calculated as follows, based on a reconciliation of the weighted-average common shares outstanding on a basic and diluted basis:

			Three Months Ended						Six Months Ended
			June 30,						June 30,
			2024			2023			2024			2023
			(In thousands, except per share amounts)
Net income			$	77,929		$	56,836		$	30,301		$	15,516
Weighted average common shares outstanding - basic			56,611			56,566			56,601			56,566
Effect of dilutive performance shares and restricted stock units			200			33			190			17
Weighted average common shares outstanding - diluted			56,811			56,599			56,791			56,583
Shares excluded from the calculation of diluted loss per share			16			—			21			—
Net income per share - basic			$	1.38		$	1.00		$	.54		$	.27
Net income per share - diluted			$	1.37		$	1.00		$	.53		$	.27

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The after-tax changes in the components of accumulated other comprehensive loss were as follows:

			Net Unrealized Loss on Derivative  Instruments  Qualifying as Hedges			Postretirement  Liability Adjustment						Total Accumulated  Other Comprehensive  Loss
			(In thousands)
As of December 31, 2023			$	—		$	(11,319)					$	(11,319)
Amounts reclassified from accumulated other comprehensive loss			—			78						78
Net current-period other comprehensive income			—			78						78
At March 31, 2024			$	—		$	(11,241)					$	(11,241)
Amounts reclassified from accumulated other comprehensive loss			—			77						77
Net current-period other comprehensive income			—			77						77
At June 30, 2024			$	—		$	(11,164)					$	(11,164)

			Net Unrealized Loss on Derivative  Instruments  Qualifying as Hedges			Postretirement  Liability Adjustment						Total Accumulated  Other Comprehensive  Loss
			(In thousands)
As of December 31, 2022			$	(90)		$	(12,262)					$	(12,352)
Amounts reclassified from accumulated other comprehensive loss			46			47						93
Net current-period other comprehensive income			46			47						93
At March 31, 2023			$	(44)		$	(12,215)					$	(12,259)
Other comprehensive loss before reclassification			—			(17)						(17)
Amounts reclassified from accumulated other comprehensive loss			44			48						92
Net current-period other comprehensive income			44			31						75
At June 30, 2023			$	—		$	(12,184)					$	(12,184)

The following amounts were reclassified out of accumulated other comprehensive loss into net income. The amounts presented in parenthesis indicate a decrease to net income on the Consolidated Statements of Operations. The reclassifications were as follows:

			Three Months Ended						Six Months Ended						Location on Consolidated Statements of Operations
			June 30,						June 30,
			2024			2023			2024			2023
			(In thousands)
Reclassification adjustment for loss on derivative instruments included in net income			$	—		$	(57)		$	—		$	(118)		Interest expense
			—			13			—			28			Income taxes
			—			(44)			—			(90)
Amortization of postretirement liability losses included in net periodic benefit cost			(102)			(63)			(205)			(126)			Other income
			25			15			50			31			Income taxes
			(77)			(48)			(155)			(95)
Total reclassifications			$	(77)		$	(92)		$	(155)		$	(185)

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Revenue is recognized when a performance obligation is satisfied by transferring control over a product or service to a customer. Revenue includes revenue from the sales of construction materials and contracting services. Revenue is measured based on consideration specified in a contract with a customer and excludes any sales incentives and amounts collected on behalf of third parties. Knife River is considered an agent for certain taxes collected from customers. As such, we present revenues net of these taxes at the time of sale to be remitted to governmental authorities, including sales and use taxes. Revenue for construction materials is recognized at a point in time when delivery of the products has taken place. Contracting revenue is recognized over time using an input method based on the cost-to-cost measure of progress on a project.

Disaggregation

In the following tables, revenue is disaggregated by category for each segment and includes sales of materials to both third parties and internal customers. Due to consolidation requirements, the internal sales revenues must be eliminated against the construction materials product used in downstream materials and contracting services to arrive at the external operating revenues. We believe this level of disaggregation best depicts how the nature, amount, timing and uncertainty of revenue and cash flows are affected by economic factors. For more information on the Company’s reportable segments, see Note 14.

Three Months Ended June 30, 2024			Pacific			Northwest			Mountain			Central			Energy Services			Corporate Services and Eliminations			Total
			(In thousands)
Aggregates			$	31,259		$	53,061		$	31,138		$	42,943		$	—		$	—		$	158,401
Ready-mix concrete			36,667			45,660			34,967			62,225			—			—			179,519
Asphalt			8,622			32,529			32,860			45,268			—			—			119,279
Liquid asphalt			—			—			—			—			65,304			—			65,304
Other			42,357			5,574			7			10,875			14,386			4,511			77,710
Contracting services public-sector			20,713			71,299			90,023			102,820			—			—			284,855
Contracting services private-sector			14,222			25,596			41,552			5,549			—			—			86,919
Internal sales			(22,013)			(33,494)			(36,778)			(55,077)			(13,447)			(4,272)			(165,081)
Revenues from contracts with customers			$	131,827		$	200,225		$	193,769		$	214,603		$	66,243		$	239		$	806,906

Three Months Ended June 30, 2023			Pacific			Northwest			Mountain			Central			Energy Services			Corporate Services and Eliminations			Total
			(In thousands)
Aggregates			$	27,446		$	47,966		$	28,866		$	42,138		$	—		$	—		$	146,416
Ready-mix concrete			40,526			44,583			34,506			65,283			—			—			184,898
Asphalt			6,275			34,518			29,472			54,672			—			—			124,937
Liquid asphalt			—			—			—			—			72,920			—			72,920
Other			39,802			4,335			8			10,909			13,849			1,341			70,244
Contracting services public-sector			16,848			53,301			80,381			114,025			—			—			264,555
Contracting services private-sector			16,575			29,353			37,317			5,637			—			—			88,882
Internal sales			(22,393)			(35,322)			(34,796)			(61,630)			(13,706)			184			(167,663)
Revenues from contracts with customers			$	125,079		$	178,734		$	175,754		$	231,034		$	73,063		$	1,525		$	785,189

Six Months Ended June 30, 2024			Pacific			Northwest			Mountain			Central			Energy Services			Corporate Services and Eliminations			Total
			(In thousands)
Aggregates			$	50,809		$	92,459		$	40,592		$	58,814		$	—		$	—		$	242,674
Ready-mix concrete			67,887			77,436			48,803			85,248			—			—			279,374
Asphalt			10,969			40,766			33,690			50,326			—			—			135,751
Liquid asphalt			—			—			—			—			76,340			—			76,340
Other			67,686			9,147			13			12,773			17,448			9,654			116,721
Contracting services public-sector			26,188			107,343			115,882			123,853			—			—			373,266
Contracting services private-sector			22,296			40,628			55,355			5,724			—			—			124,003
Internal sales			(35,621)			(48,402)			(40,740)			(61,173)			(16,428)			(9,269)			(211,633)
Revenues from contracts with customers			$	210,214		$	319,377		$	253,595		$	275,565		$	77,360		$	385		$	1,136,496

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Six Months Ended June 30, 2023			Pacific			Northwest			Mountain			Central			Energy Services			Corporate Services and Eliminations			Total
			(In thousands)
Aggregates			$	46,143		$	90,540		$	38,532		$	54,722		$	—		$	—		$	229,937
Ready-mix concrete			66,670			78,488			48,876			87,633			—			—			281,667
Asphalt			7,591			41,445			30,282			59,238			—			—			138,556
Liquid asphalt			—			—			—			—			81,206			—			81,206
Other			63,222			7,016			11			12,495			16,040			1,767			100,551
Contracting services public-sector			20,819			70,304			108,619			136,885			—			—			336,627
Contracting services private-sector			19,474			55,115			50,762			6,442			—			—			131,793
Internal sales			(33,197)			(48,254)			(40,710)			(68,761)			(15,928)			(398)			(207,248)
Revenues from contracts with customers			$	190,722		$	294,654		$	236,372		$	288,654		$	81,318		$	1,369		$	1,093,089

The timing of revenue recognition may differ from the timing of invoicing to customers. The timing of invoicing to customers does not necessarily correlate with the timing of revenues being recognized under the cost-to-cost method of accounting. Contracts from contracting services are billed as work progresses in accordance with agreed upon contractual terms. Generally, billing to the customer occurs contemporaneous to revenue recognition. A variance in timing of the billings may result in a contract asset or a contract liability. A contract asset occurs when revenues are recognized under the cost-to-cost measure of progress, which exceeds amounts billed on uncompleted contracts. Such amounts will be billed as standard contract terms allow, usually based on various measures of performance or achievement. A contract liability occurs when there are billings in excess of revenues recognized under the cost-to-cost measure of progress on uncompleted contracts. Contract liabilities decrease as revenue is recognized from the satisfaction of the related performance obligation.

The changes in contract assets and liabilities were as follows:

			June 30, 2024			December 31, 2023			Change			Location on Consolidated Balance Sheets
			(In thousands)
Contract assets			$	49,150		$	27,293		$	21,857		Costs and estimated earnings in excess of billings on uncompleted contracts
Contract liabilities			(45,123)			(51,376)			6,253			Billings in excess of costs and estimated earnings on uncompleted contracts
Net contract assets (liabilities)			$	4,027		$	(24,083)		$	28,110

			June 30, 2023			December 31, 2022			Change			Location on Consolidated Balance Sheets
			(In thousands)
Contract assets			$	58,020		$	31,145		$	26,875		Costs and estimated earnings in excess of billings on uncompleted contracts
Contract liabilities			(44,590)			(39,843)			(4,747)			Billings in excess of costs and estimated earnings on uncompleted contracts
Net contract assets (liabilities)			$	13,430		$	(8,698)		$	22,128

The Company recognized $14.4 million and $44.9 million in revenue for the three and six months ended June 30, 2024, respectively, which was previously included in contract liabilities at December 31, 2023. The Company recognized $11.4 million and $31.7 million in revenue for the three and six months ended June 30, 2023, respectively, which was previously included in contract liabilities at December 31, 2022.

The Company recognized a net increase in revenues of $15.1 million and $21.2 million for the three and six months ended June 30, 2024, respectively, from performance obligations satisfied in prior periods. The Company recognized a net increase in revenues of $7.4 million and $8.1 million for the three and six months ended June 30, 2023, respectively, from performance obligations satisfied in prior periods.

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Remaining performance obligations

The remaining performance obligations, also referred to as backlog, include unrecognized revenues that we reasonably expect to be realized. These unrecognized revenues can include: projects that have a written award, a letter of intent, a notice to proceed, an agreed upon work order to perform work on mutually accepted terms and conditions, and change orders or claims to the extent management believes additional contract revenues will be earned and are deemed probable of collection. The majority of our contracts for contracting services have an original duration of less than one year.

At June 30, 2024, the Company's remaining performance obligations were $988.5 million. We expect to recognize the following revenue amounts in future periods related to these remaining performance obligations: $936.7 million within the next 12 months or less; $44.0 million within the next 13 to 24 months; and $7.8 million in 25 months or more.

The changes in the carrying amount of goodwill were as follows:

			Balance at January 1, 2024			Goodwill Acquired During the Year			Measurement Period Adjustments			Reallocation of Goodwill			Balance at June 30, 2024
			(In thousands)
Pacific			$	32,621		$	—		$	—		$	—		$	32,621
Northwest			90,978			—			—			—			90,978
Mountain			26,816			—			—			—			26,816
North Central			75,879			735			—			—			76,614
South			38,708			—			—			—			38,708
Energy Services			9,476			—			—			—			9,476
Total			$	274,478		$	735		$	—		$	—		$	275,213

			Balance at January 1, 2023			Goodwill Acquired During the Year			Measurement Period Adjustments			Reallocation of Goodwill			Balance at June 30, 2023
			(In thousands)
Pacific			$	38,339		$	—		$	(62)		$	—		$	38,277
Northwest			90,978			—			—			—			90,978
Mountain			26,816			—			—			—			26,816
North Central			75,879			—			—			—			75,879
South			38,708			—			—			—			38,708
Energy Services			3,820			—			—			—			3,820
Total			$	274,540		$	—		$	(62)		$	—		$	274,478

			Balance at January 1, 2023			Goodwill Acquired During the Year			Measurement Period Adjustments			Reallocation of Goodwill			Balance at December 31, 2023
			(In thousands)
Pacific			$	38,339		$	—		$	(62)		$	(5,656)		$	32,621
Northwest			90,978			—			—			—			90,978
Mountain			26,816			—			—			—			26,816
North Central			75,879			—			—			—			75,879
South			38,708			—			—			—			38,708
Energy Services			3,820			—			—			5,656			9,476
Total			$	274,540		$	—		$	(62)		$	—		$	274,478

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Other amortizable intangible assets were as follows:

			June 30, 2024			June 30, 2023			December 31, 2023
			(In thousands)
Customer relationships			$	18,868		$	18,540		$	18,540
Less accumulated amortization			9,977			8,235			9,102
			8,891			10,305			9,438
Noncompete agreements			3,784			4,039			4,039
Less accumulated amortization			3,283			3,239			3,473
			501			800			566
Other			1,796			2,479			2,479
Less accumulated amortization			1,044			1,474			1,662
			752			1,005			817
Total			$	10,144		$	12,110		$	10,821

Amortization expense for amortizable intangible assets for the three and six months ended June 30, 2024, was $526,000 and $1.1 million, respectively. Amortization expense for amortizable intangible assets for the three and six months ended June 30, 2023, was $653,000 and $1.3 million, respectively. Estimated amortization expense for identifiable intangible assets as of June 30, 2024, was:

			Remainder of 2024			2025			2026			2027			2028			Thereafter
			(In thousands)
Amortization expense			$	1,192		$	1,964		$	1,784		$	1,761		$	1,717		$	1,726

Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability (an exit price) in an orderly transaction between market participants at the measurement date. The fair value guidance establishes a hierarchy for grouping assets and liabilities, based on the significance of inputs. The estimated fair values of the Company's assets and liabilities measured on a recurring basis are determined using the market approach.

Financial instruments measured at fair value on a recurring basis

We measure our investments in certain fixed-income and equity securities at fair value with changes in fair value recognized in income. We anticipate using these investments, which consist of insurance contracts, to satisfy our obligations under our unfunded, nonqualified defined benefit and defined contribution plans for our executive officers and certain key management employees, and invests in these fixed-income and equity securities for the purpose of earning investment returns and capital appreciation. These investments, which totaled $27.3 million, $19.1 million and $24.9 million at June 30, 2024 and 2023, and December 31, 2023, respectively, are classified as investments on the Consolidated Balance Sheets. The net unrealized gains on these investments were $392,000 and $197,000 for the three months ended and $1.6 million and $1.1 million for the six months ended June 30, 2024 and 2023, respectively. The change in fair value, which is considered part of the cost of the plan, is classified in other income on the Consolidated Statements of Operations.

The Company's assets measured at fair value on a recurring basis were as follows:

			Fair Value Measurements at June 30, 2024, Using
			Quoted Prices in Active Markets for Identical Assets (Level 1)			Significant Other Observable Inputs (Level 2)			Significant Unobservable Inputs (Level 3)			Balance at June 30, 2024
			(In thousands)
Assets:
Money market funds			$	—		$	3,982		$	—		$	3,982
Insurance contracts*			—			27,289			—			27,289
Total assets measured at fair value			$	—		$	31,271		$	—		$	31,271

*    The insurance contracts invest approximately 36 percent in fixed-income investments, 23 percent in common stock of large-cap companies, 15 percent in cash equivalents, 9 percent in common stock of mid-cap companies, 9 percent target date investments, 5 percent in common stock of small-cap companies, 1 percent in international investments, 1 percent in real estate investments and 1 percent in high yield investments.

---

			Fair Value Measurements at June 30, 2023, Using
			Quoted Prices in Active Markets for Identical Assets (Level 1)			Significant Other Observable Inputs (Level 2)			Significant Unobservable Inputs (Level 3)			Balance at June 30, 2023
			(In thousands)
Assets:
Money market funds			$	—		$	7,529		$	—		$	7,529
Insurance contracts*			—			19,141			—			19,141
Total assets measured at fair value			$	—		$	26,670		$	—		$	26,670

*    The insurance contracts invest approximately 47 percent in fixed-income investments, 20 percent in cash equivalents, 15 percent in common stock of large-cap companies, 8 percent in common stock of mid-cap companies, 6 percent in common stock of small-cap companies and 4 percent target date investments.

			Fair Value Measurements at December 31, 2023, Using
			Quoted Prices in Active Markets for Identical Assets  (Level 1)			Significant Other Observable Inputs (Level 2)			Significant Unobservable Inputs  (Level 3)			Balance at December 31, 2023
			(In thousands)
Assets:
Money market funds			$	—		$	3,241		$	—		$	3,241
Insurance contracts*			—			24,896			—			24,896
Total assets measured at fair value			$	—		$	28,137		$	—		$	28,137

*    The insurance contracts invest approximately 40 percent in fixed-income investments, 19 percent in common stock of large-cap companies, 18 percent in cash equivalents, 8 percent in target date investments, 8 percent in common stock of mid-cap companies, 6 percent in common stock of small-cap companies and 1 percent in international investments.

The Company’s Level 2 money market funds are valued at the net asset value of shares held at the end of the period, based on published market quotations on active markets, or using other known sources including pricing from outside sources. The estimated fair value of the Company’s Level 2 insurance contracts is based on contractual cash surrender values that are determined primarily by investments in managed separate accounts of the insurer. These amounts approximate fair value. The managed separate accounts are valued based on other observable inputs or corroborated market data.

Though we believe the methods used to estimate fair value are consistent with those used by other market participants, the use of other methods or assumptions could result in a different estimate of fair value.

Nonfinancial instruments measured at fair value on a nonrecurring basis

We apply the provisions of the fair value measurement standard to our nonrecurring, non-financial measurements, including long-lived asset impairments. These assets are not measured at fair value on an ongoing basis but are subject to fair value adjustments only in certain circumstances. We review the carrying value of our long-lived assets, excluding goodwill, whenever events or changes in circumstances indicate that such carrying amounts may not be recoverable.

The assets and liabilities of the acquisitions that occurred during the second quarter of 2024 were calculated using a market or cost approach. The fair value of some of the assets was determined based on Level 3 inputs including estimated future cash flows, discount rates, growth rates and sales projections, all of which require significant management judgment.

The Company's long-term debt is not measured at fair value on the Consolidated Balance Sheets and the fair value is being provided for disclosure purposes only. The fair value was categorized as Level 2 in the fair value hierarchy and was based on

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discounted cash flows using current market interest rates. The estimated fair value of the Company's Level 2 long-term debt was as follows:

			June 30, 2024			June 30, 2023			December 31, 2023
			(In thousands)
Carrying amount			$	693,483		$	855,000		$	696,985
Fair value			$	712,852		$	862,420		$	725,086

The carrying amounts of our remaining financial instruments included in current assets and current liabilities approximate their fair values.

Certain debt instruments of the Company contain restrictive covenants and cross-default provisions. In order to borrow under the debt agreements, we must be in compliance with the applicable covenants and certain other conditions, all of which the Company, as applicable, was in compliance with at June 30, 2024. In the event we do not comply with the applicable covenants and other conditions, alternative sources of funding may need to be pursued.

Long-term Debt Outstanding Long-term debt outstanding was as follows:

			Weighted Average Interest Rate at June 30, 2024			June 30, 2024			June 30, 2023			December 31, 2023
						(In thousands)
Term loan agreement due on May 31, 2028			7.20		%	$	268,125		$	275,000		$	271,562
Revolving credit agreement			—		%	—			155,000			—
Senior notes due on May 1, 2031			7.75		%	425,000			425,000			425,000
Other notes due on January 1, 2061			—		%	358			511			423
Less unamortized debt issuance costs						13,945			16,382			15,326
Total long-term debt						679,538			839,129			681,659
Less current maturities						7,072			7,082			7,082
Net long-term debt						$	672,466		$	832,047		$	674,577

Schedule of Debt Maturities Long-term debt maturities, which excludes unamortized debt issuance costs, at June 30, 2024, were as follows:

			Remainder of 2024			2025			2026			2027			2028			Thereafter
			(In thousands)
Long-term debt maturities			$	3,634		$	10,473		$	13,750		$	17,188		$	223,438		$	425,000

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Cash expenditures for interest and income taxes were as follows:

			Six Months Ended
			June 30,
			2024			2023
			(In thousands)
Interest paid, net			$	27,993		$	24,802
Income taxes paid, net			$	1,662		$	558

Noncash investing and financing transactions were as follows:

			Six Months Ended
			June 30,
			2024			2023
			(In thousands)
Right-of-use assets obtained in exchange for new operating lease liabilities			$	10,844		$	7,552
Property, plant and equipment additions in accounts payable			$	5,098		$	3,359
Equity contribution from Centennial related to the Separation			$	—		$	64,724
Equity contribution to MDU Resources for asset/liability transfers related to the Separation			$	—		$	(1,548)
MDU Resources' stock issued prior to spin in connection with a business combination			$	—		$	383

We focus on the vertical integration of our products and services by offering customers a single source for construction materials and related contracting services. We operate in 14 states across the United States through our operating segments: Pacific, Northwest, Mountain, North Central, South and Energy Services. These operating segments are used to determine the Company’s reportable segments, Pacific, Northwest, Mountain, Central and Energy Services, which are based on our method of internal reporting and management of our business. Four of the reportable segments are aligned by key geographic areas due to the production of construction materials and related contracting services and one is based on product line. Each segment is led by a segment manager who reports to the Company’s chief operating officer, who is also the Company's chief operating decision maker, along with the chief executive officer. The chief operating decision maker evaluates the performance of the segments and allocates resources to them based on earnings before interest, taxes, depreciation, depletion and amortization ("EBITDA").

In the fourth quarter of 2023, we realigned our reportable segments to better support our operational strategies. The liquid asphalt and related services portion of the Pacific segment's businesses are now reported under the Energy Services segment. In addition, the North Central and South operating regions have been aggregated into one reportable segment, Central. We also reallocated certain amounts to the operating segments that were previously reported within Corporate Services. All periods have been recast to conform with the revised presentation.

Each geographic segment offers a vertically integrated suite of products and services, including aggregates, ready-mix concrete, asphalt and contracting services, while the Energy Services segment produces and supplies liquid asphalt, primarily for use in asphalt road construction, and is a supplier to some of the other segments. Each geographic segment mines, processes and sells construction aggregates (crushed stone and sand and gravel); produces and sells asphalt; and produces and sells ready-mix concrete as well as vertically integrating its contracting services to support the aggregate-based product lines. Contracting services include heavy-civil construction, asphalt and concrete paving, and site development and grading. Although not common to all locations, the geographic segments also sell cement, merchandise and other building materials and related services.

Corporate Services represents the unallocated costs of certain corporate functions, such as accounting, legal, treasury, information technology, human resources and other corporate expenses that support the operating segments. We account for intersegment sales and transfers as if the sales or transfers were to third parties. The accounting policies applicable to each segment are consistent with those used in the audited consolidated financial statements.

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The information below follows the same accounting policies as described in the audited financial statements and notes included in the Company's 2023 Annual Report. Information on the Company's segments was as follows:

			Three Months Ended						Six Months Ended
			June 30,						June 30,
			2024			2023			2024			2023
			(In thousands)
External operating revenues:
Pacific			$	131,827		$	125,079		$	210,214		$	190,722
Northwest			200,225			178,734			319,377			294,654
Mountain			193,769			175,754			253,595			236,372
Central			214,603			231,034			275,565			288,654
Energy Services			66,243			73,063			77,360			81,318
Total reportable segment external operating revenues			$	806,667		$	783,664		$	1,136,111		$	1,091,720
Intersegment operating revenues:
Pacific			$	22,013		$	22,393		$	35,621		$	33,197
Northwest			33,494			35,322			48,402			48,254
Mountain			36,778			34,796			40,740			40,710
Central			55,077			61,630			61,173			68,761
Energy Services			13,447			13,706			16,428			15,928
Total reportable segment intersegment operating revenues			$	160,809		$	167,847		$	202,364		$	206,850
EBITDA:
Pacific			$	17,789		$	17,457		$	17,046		$	17,605
Northwest			50,762			38,871			70,916			52,868
Mountain			43,119			30,323			37,054			26,570
Central			36,188			28,399			17,466			11,500
Energy Services			19,367			21,781			16,884			18,804
Total reportable segment EBITDA			$	167,225		$	136,831		$	159,366		$	127,347

A reconciliation of consolidated operating revenues to reportable segment operating revenues is as follows:

			Three Months Ended						Six Months Ended
			June 30,						June 30,
			2024			2023			2024			2023
			(In thousands)
Consolidated operating revenues			$	806,906		$	785,189		$	1,136,496		$	1,093,089
Plus:
Intersegment operating revenues			165,081			167,663			211,633			207,248
Less:
Corporate Services revenue			4,511			1,341			9,654			1,767
Total reportable segment operating revenues			$	967,476		$	951,511		$	1,338,475		$	1,298,570

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A reconciliation of consolidated net income before income taxes to reportable segment EBITDA is as follows:

			Three Months Ended						Six Months Ended
			June 30,						June 30,
			2024			2023			2024			2023
			(In thousands)
Total consolidated net income before income taxes			$	104,114		$	76,855		$	40,160		$	23,623
Plus:
Depreciation, depletion and amortization			34,512			31,130			66,724			60,760
Interest expense, net*			12,809			17,130			23,955			26,625
Less:
Corporate Services EBITDA			(15,790)			(11,716)			(28,527)			(16,339)
Total EBITDA for reportable segments			$	167,225		$	136,831		$	159,366		$	127,347
*Interest, net is interest expense net of interest income.

The Company is party to claims and lawsuits arising out of its business and that of its consolidated subsidiaries, which may include, but are not limited to, matters involving property damage, personal injury, and environmental, contractual and statutory obligations. We accrue a liability for those contingencies when the incurrence of a loss is probable and the amount can be reasonably estimated. If a range of amounts can be reasonably estimated and no amount within the range is a better estimate than any other amount, then the minimum of the range is accrued. We do not accrue liabilities when the likelihood that the liability has been incurred is probable but the amount cannot be reasonably estimated or when the liability is believed to be only reasonably possible or remote. For contingencies where an unfavorable outcome is probable or reasonably possible and which are material, we disclose the nature of the contingency and, in some circumstances, an estimate of the possible loss. Accruals are based on the best information available, but in certain situations management is unable to estimate an amount or range of a reasonably possible loss including, but not limited to when: (1) the damages are unsubstantiated or indeterminate, (2) the proceedings are in the early stages, (3) numerous parties are involved, or (4) the matter involves novel or unsettled legal theories.

At June 30, 2024 and 2023, and December 31, 2023, we accrued contingent liabilities as a result of litigation, which have not been discounted, of $3.2 million, $970,000 and $873,000, respectively. At June 30, 2024 and 2023 and December 31, 2023, we also recorded corresponding insurance receivables of $0, $325,000 and $42,000, respectively, related to the accrued liabilities. Most of these claims and lawsuits are covered by insurance, thus the Company's exposure is typically limited to its deductible amount. Management will continue to monitor each matter and adjust accruals as might be warranted based on new information and further developments. Management believes that the outcomes with respect to probable and reasonably possible losses in excess of the amounts accrued, net of insurance recoveries, while uncertain, either cannot be estimated or will not have a material effect upon the Company's financial position, results of operations or cash flows. Unless otherwise required by GAAP, legal costs are expensed as they are incurred.

Environmental matters

The Company is a party to claims for the cleanup of a superfund site in Portland, Oregon. There were no material changes to the environmental matters that were previously reported in the audited financial statements and notes included in the Company's 2023 Annual Report.

Guarantees

Knife River and certain of its subsidiaries have outstanding obligations to third parties where the Company has guaranteed their performance. These guarantees are related to contracts for contracting services and certain other guarantees. At June 30, 2024, the fixed maximum amounts guaranteed under these agreements aggregated to $11.5 million, all of which have no scheduled maturity date. Certain of the guarantees also have no fixed maximum amounts specified. There were no amounts outstanding under the previously mentioned guarantees at June 30, 2024.

Knife River and certain of its subsidiaries have outstanding letters of credit to third parties related to insurance policies, cement purchases and other agreements. At June 30, 2024, the fixed maximum amounts guaranteed under these letters of credit aggregated $20.9 million. At June 30, 2024, the amounts of scheduled expiration of the maximum amounts guaranteed under these letters of credit aggregate to $335,000 in 2024, $20.5 million in 2025, $0 in 2026 and $104,000 in 2027. There were no amounts outstanding under the previously mentioned letters of credit at June 30, 2024.

In the normal course of business, we have surety bonds related to contracts for contracting services, reclamation obligations and insurance policies of its subsidiaries. In the event a subsidiary of Knife River does not fulfill a bonded obligation, the Company would be responsible to the surety bond company for completion of the bonded contract or obligation. A large portion of the surety bonds are expected to expire within the next 12 months; however, we will likely continue to enter into surety bonds for our

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subsidiaries in the future. At June 30, 2024, approximately $894.2 million of surety bonds were outstanding, which were not reflected on the Consolidated Balance Sheet.

Transition services agreements

As part of the Separation, MDU Resources is providing transition services to Knife River and Knife River is providing transition services to MDU Resources in accordance with the Transition Services Agreement entered into on May 30, 2023. The Company paid $413,000 and $599,000 for the three months ended and $1.2 million and $599,000 for the six months ended June 30, 2024 and 2023, respectively, related to these activities, which were reflected in selling, general and administrative expenses on the Consolidated Statements of Operations. The Company received $62,000 and $277,000 for the three months ended and $138,000 and $277,000 for the six months ended June 30, 2024 and 2023, respectively, related to these activities, which were reflected in other income on the Consolidated Statements of Operations. The majority of the transition services were completed over a period of one year after the Separation. The Company expects minimal continued services by Knife River to MDU Resources through May 2025.

For additional information on the presentation of related-party transactions, see Note 2.

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v3.24.2.u1

Cover page - shares	6 Months Ended
	Jun. 30, 2024	Aug. 01, 2024
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2024
Document Transition Report	false
Entity File Number	1-41642
Entity Registrant Name	Knife River Corporation
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	92-1008893
Entity Address, Address Line One	1150 West Century Avenue
Entity Address, Address Line Two	P.O. Box 5568
Entity Address, City or Town	Bismarck
Entity Address, State or Province	ND
Entity Address, Postal Zip Code	58506-5568
City Area Code	701
Local Phone Number	530-1400
Title of 12(b) Security	Common Stock, $0.01 par value
Trading Symbol	KNF
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity common stock, shares outstanding		56,612,705
Entity Central Index Key	0001955520
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q2
Amendment Flag	false

v3.24.2.u1

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Revenue:
Revenue	$ 806,906	$ 785,189	$ 1,136,496	$ 1,093,089
Cost of revenue:
Cost of revenue	630,686	632,206	953,783	936,011
Gross profit	176,220	152,983	182,713	157,078
Selling, general and administrative expenses	59,474	59,450	119,695	108,108
Operating income	116,746	93,533	63,018	48,970
Interest expense	13,936	19,156	27,912	28,651
Other income	1,304	2,478	5,054	3,304
Income before income taxes	104,114	76,855	40,160	23,623
Income tax expense	26,185	20,019	9,859	8,107
Net income	$ 77,929	$ 56,836	$ 30,301	$ 15,516
Net income per share:
Basic (in dollars per share)	$ 1.38	$ 1.00	$ 0.54	$ 0.27
Diluted (in dollars per share)	$ 1.37	$ 1.00	$ 0.53	$ 0.27
Weighted average common shares outstanding:
Basic (in shares)	56,611	56,566	56,601	56,566
Diluted (in shares)	56,811	56,599	56,791	56,583
Construction materials
Revenue:
Revenue	$ 435,132	$ 431,752	$ 639,227	$ 624,669
Cost of revenue:
Cost of revenue	310,322	316,179	520,152	510,308
Contracting services
Revenue:
Revenue	371,774	353,437	497,269	468,420
Cost of revenue:
Cost of revenue	$ 320,364	$ 316,027	$ 433,631	$ 425,703

v3.24.2.u1

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 77,929	$ 56,836	$ 30,301	$ 15,516
Other comprehensive income:
Reclassification adjustment for loss on derivative instruments included in net income, net of tax of $0 and $13 for the three months ended and $0 and $28 for the six months ended in 2024 and 2023, respectively	0	44	0	90
Postretirement liability adjustment:
Postretirement liability losses arising during the period, net of tax of $0 and $(6) for the three months ended and $0 and $(6) for the six months ended in 2024 and 2023, respectively	0	(17)	0	(17)
Amortization of postretirement liability losses included in net periodic benefit cost, net of tax of $25 and $15 for the three months ended and $50 and $31 for the six months ended in 2024 and 2023, respectively	77	48	155	95
Postretirement liability adjustment	77	31	155	78
Other comprehensive income	77	75	155	168
Comprehensive income attributable to common stockholders	$ 78,006	$ 56,911	$ 30,456	$ 15,684

v3.24.2.u1

Consolidated Statements of Comprehensive Income (Parentheticals) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Statement of Comprehensive Income [Abstract]
Reclassification adjustment for loss on derivative instruments included in net income, tax	$ 0	$ 13	$ 0	$ 28
Postretirement liability losses arising during the period, net of tax	0	(6)	0	(6)
Amortization of postretirement liability losses included in net periodic benefit cost, tax	$ 25	$ 15	$ 50	$ 31

v3.24.2.u1

Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023	Jun. 30, 2023
Current assets:
Cash, cash equivalents and restricted cash	$ 57,169	$ 262,320	$ 68,489
Receivables, net	422,941	266,785	418,620
Costs and estimated earnings in excess of billings on uncompleted contracts	49,150	27,293	58,020
Inventories	385,378	319,623	374,377
Prepayments and other current assets	35,049	37,522	38,820
Total current assets	949,687	913,543	958,326
Noncurrent assets:
Property, plant and equipment	2,672,253	2,579,734	2,533,435
Less accumulated depreciation, depletion and amortization	1,316,872	1,264,687	1,221,966
Net property, plant and equipment	1,355,381	1,315,047	1,311,469
Goodwill	275,213	274,478	274,478
Other intangible assets, net	10,144	10,821	12,110
Operating lease right-of-use assets	47,818	44,706	45,933
Investments and other	44,619	41,218	40,581
Total noncurrent assets	1,733,175	1,686,270	1,684,571
Total assets	2,682,862	2,599,813	2,642,897
Current liabilities:
Long-term debt - current portion	7,072	7,082	7,082
Accounts payable	164,188	107,656	174,603
Billings in excess of costs and estimated earnings on uncompleted contracts	45,123	51,376	44,590
Taxes payable	15,602	9,300	29,878
Accrued compensation	29,208	48,098	26,041
Accrued interest	7,167	7,247	7,906
Current operating lease liabilities	13,615	12,948	14,067
Other accrued liabilities	96,334	103,564	80,189
Total current liabilities	378,309	347,271	384,356
Noncurrent liabilities:
Long-term debt	672,466	674,577	832,047
Deferred income taxes	179,197	174,542	170,502
Noncurrent operating lease liabilities	34,203	31,758	31,866
Other	119,981	105,653	129,274
Total liabilities	1,384,156	1,333,801	1,548,045
Commitments and contingencies
Commitments and contingencies
Stockholders' equity:
Common stock, 300,000,000 shares authorized, $0.01 par value, 57,043,841 shares issued and 56,612,705 shares outstanding at June 30, 2024; 56,997,350 shares issued and 56,566,214 shares outstanding at June 30, 2023; 57,009,542 shares issued and 56,578,406 shares outstanding at December 31, 2023	570	570	570
Other paid-in capital	616,757	614,513	611,562
Retained earnings	696,169	665,874	498,530
Treasury stock held at cost - 431,136 shares	(3,626)	(3,626)	(3,626)
Accumulated other comprehensive loss	(11,164)	(11,319)	(12,184)
Total stockholders' equity	1,298,706	1,266,012	1,094,852
Total liabilities and stockholders' equity	$ 2,682,862	$ 2,599,813	$ 2,642,897

v3.24.2.u1

Consolidated Balance Sheets (Parentheticals) - $ / shares	Jun. 30, 2024	Dec. 31, 2023	Jun. 30, 2023
Statement of Financial Position [Abstract]
Common stock, authorized (in shares)	300,000,000	300,000,000	300,000,000
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01	$ 0.01
Common stock, issued (in shares)	57,043,841	57,009,542	56,997,350
Common stock, outstanding (in shares)	56,612,705	56,578,406	56,566,214
Treasury stock held at cost (in shares)	431,136	431,136	431,136

v3.24.2.u1

Consolidated Statements of Equity - USD ($) $ in Thousands	Total	Common Stock	Other Paid-in Capital	Retained Earnings	MDU Resources' Stock Held by Subsidiary	Treasury Stock	Accumula-ted Other Comprehe-nsive Loss
Beginning balance (in shares) at Dec. 31, 2022		80,000
Beginning balance at Dec. 31, 2022	$ 1,028,589	$ 800	$ 549,106	$ 494,661	$ (3,626)	$ 0	$ (12,352)
Common stock held by subsidiary, beginning balance (in shares) at Dec. 31, 2022					(538,921)
Treasury stock, beginning balance (in shares) at Dec. 31, 2022						0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(41,320)			(41,320)
Other comprehensive income	93						93
Stock-based compensation expense	414		453	(39)
Net transfers to Centennial	(13,007)		(1,385)	(11,622)
Ending balance (in shares) at Mar. 31, 2023		80,000
Common stock held by subsidiary, ending balance (in shares) at Mar. 31, 2023					(538,921)
Treasury stock, ending balance (in shares) at Mar. 31, 2023						0
Ending balance at Mar. 31, 2023	974,769	$ 800	548,174	441,680	$ (3,626)	$ 0	(12,259)
Beginning balance (in shares) at Dec. 31, 2022		80,000
Beginning balance at Dec. 31, 2022	1,028,589	$ 800	549,106	494,661	$ (3,626)	$ 0	(12,352)
Common stock held by subsidiary, beginning balance (in shares) at Dec. 31, 2022					(538,921)
Treasury stock, beginning balance (in shares) at Dec. 31, 2022						0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	15,516
Other comprehensive income	$ 168
Ending balance (in shares) at Jun. 30, 2023	56,566,214	56,997,350
Common stock held by subsidiary, ending balance (in shares) at Jun. 30, 2023					0
Treasury stock, ending balance (in shares) at Jun. 30, 2023	(431,136)					(431,136)
Ending balance at Jun. 30, 2023	$ 1,094,852	$ 570	611,562	498,530	$ 0	$ (3,626)	(12,184)
Beginning balance (in shares) at Mar. 31, 2023		80,000
Beginning balance at Mar. 31, 2023	974,769	$ 800	548,174	441,680	$ (3,626)	$ 0	(12,259)
Common stock held by subsidiary, beginning balance (in shares) at Mar. 31, 2023					(538,921)
Treasury stock, beginning balance (in shares) at Mar. 31, 2023						0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	56,836			56,836
Other comprehensive income	75						75
Stock-based compensation expense	226		212	14
Transfer of MDU Resources' stock held by subsidiary (in share)					538,921
Transfer of MDU Resources' stock held by subsidiary	3,626				$ 3,626
Receipt of treasury stock at cost (in share)						(431,136)
Receipt of treasury stock at cost	(3,626)					$ (3,626)
Retirement of historical common stock in connection with the Separation (in share)		(80,000)
Retirement of historical common stock in connection with the Separation	0	$ (800)	800
Issuance of common stock in connection with the Separation (in shares)		56,997,350
Issuance of common stock in connection with the Separation	(26)	$ 570	(596)
Net transfers to Centennial	$ 62,972		62,972
Ending balance (in shares) at Jun. 30, 2023	56,566,214	56,997,350
Common stock held by subsidiary, ending balance (in shares) at Jun. 30, 2023					0
Treasury stock, ending balance (in shares) at Jun. 30, 2023	(431,136)					(431,136)
Ending balance at Jun. 30, 2023	$ 1,094,852	$ 570	611,562	498,530	$ 0	$ (3,626)	(12,184)
Beginning balance (in shares) at Dec. 31, 2023	56,578,406	57,009,542
Beginning balance at Dec. 31, 2023	$ 1,266,012	$ 570	614,513	665,874	$ 0	$ (3,626)	(11,319)
Common stock held by subsidiary, beginning balance (in shares) at Dec. 31, 2023					0
Treasury stock, beginning balance (in shares) at Dec. 31, 2023	(431,136)					(431,136)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	$ (47,629)			(47,629)
Other comprehensive income	78						78
Stock-based compensation expense	1,811		1,811
Common stock issued for employee compensation, net of tax withholding (in shares)		31,298
Common stock issued for employee compensation, net of tax withholding	(1,645)		(1,645)
Ending balance (in shares) at Mar. 31, 2024		57,040,840
Common stock held by subsidiary, ending balance (in shares) at Mar. 31, 2024					0
Treasury stock, ending balance (in shares) at Mar. 31, 2024						(431,136)
Ending balance at Mar. 31, 2024	$ 1,218,627	$ 570	614,679	618,245	$ 0	$ (3,626)	(11,241)
Beginning balance (in shares) at Dec. 31, 2023	56,578,406	57,009,542
Beginning balance at Dec. 31, 2023	$ 1,266,012	$ 570	614,513	665,874	$ 0	$ (3,626)	(11,319)
Common stock held by subsidiary, beginning balance (in shares) at Dec. 31, 2023					0
Treasury stock, beginning balance (in shares) at Dec. 31, 2023	(431,136)					(431,136)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	$ 30,301
Other comprehensive income	$ 155
Ending balance (in shares) at Jun. 30, 2024	56,612,705	57,043,841
Common stock held by subsidiary, ending balance (in shares) at Jun. 30, 2024					0
Treasury stock, ending balance (in shares) at Jun. 30, 2024	(431,136)					(431,136)
Ending balance at Jun. 30, 2024	$ 1,298,706	$ 570	616,757	696,169	$ 0	$ (3,626)	(11,164)
Beginning balance (in shares) at Mar. 31, 2024		57,040,840
Beginning balance at Mar. 31, 2024	1,218,627	$ 570	614,679	618,245	$ 0	$ (3,626)	(11,241)
Common stock held by subsidiary, beginning balance (in shares) at Mar. 31, 2024					0
Treasury stock, beginning balance (in shares) at Mar. 31, 2024						(431,136)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	77,929			77,929
Other comprehensive income	77						77
Stock-based compensation expense	2,101		2,106	(5)
Common stock issued for board of director fees (in share)		3,001
Common stock issued for board of director fees	$ (28)		(28)
Ending balance (in shares) at Jun. 30, 2024	56,612,705	57,043,841
Common stock held by subsidiary, ending balance (in shares) at Jun. 30, 2024					0
Treasury stock, ending balance (in shares) at Jun. 30, 2024	(431,136)					(431,136)
Ending balance at Jun. 30, 2024	$ 1,298,706	$ 570	$ 616,757	$ 696,169	$ 0	$ (3,626)	$ (11,164)

v3.24.2.u1

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023
Operating activities:
Net income (loss)	$ 30,301	$ 15,516
Adjustments to reconcile net income to net cash used in operating activities:
Depreciation, depletion and amortization	66,724	60,760
Deferred income taxes	4,739	(5,355)
Provision for credit losses	277	1,015
Amortization of debt issuance costs	1,381	2,059
Employee stock-based compensation costs	3,686	665
Pension and postretirement benefit plan net periodic benefit cost	605	595
Unrealized gains on investments	(1,604)	(1,282)
Gains on sales of assets	(5,626)	(3,356)
Changes in current assets and liabilities, net of acquisitions:
Receivables	(178,102)	(236,395)
Due from related-party	0	16,050
Inventories	(65,434)	(51,100)
Other current assets	2,473	(20,853)
Accounts payable	57,853	102,566
Due to related-party	0	(7,310)
Other current liabilities	(12,831)	25,598
Pension and postretirement benefit plan contributions	(283)	(292)
Other noncurrent changes	6,064	30,741
Net cash used in operating activities	(89,777)	(70,378)
Investing activities:
Capital expenditures	(103,623)	(66,578)
Acquisitions, net of cash acquired	(10,208)	0
Net proceeds from sale or disposition of property and other	6,765	4,117
Investments	(3,132)	(1,655)
Net cash used in investing activities	(110,198)	(64,116)
Financing activities:
Issuance of long-term related-party notes, net	0	205,275
Issuance of long-term debt	0	855,000
Repayment of long-term debt	(3,503)	(127)
Debt issuance costs	0	(16,640)
Proceeds from issuance of common stock	0	(26)
Tax withholding on stock-based compensation	(1,673)	0
Net transfers to Centennial	0	(850,589)
Net cash provided by (used in) financing activities	(5,176)	192,893
Increase (decrease) in cash, cash equivalents and restricted cash	(205,151)	58,399
Cash, cash equivalents and restricted cash -- beginning of year	262,320	10,090
Cash, cash equivalents and restricted cash -- end of period	$ 57,169	$ 68,489

v3.24.2.u1

Background	6 Months Ended
	Jun. 30, 2024
Restructuring and Related Activities [Abstract]
Background	Background Knife River is a people-first construction materials and contracting services company. We provide construction materials and contracting services to build safe roads, bridges, airport runways and other critical infrastructure needs that connect people with where they want to go and with the supplies they need. Knife River is one of the leading providers of crushed stone and sand and gravel in the United States and operates across 14 states. We conduct our operations through five reportable segments: Pacific, Northwest, Mountain, Central and Energy Services. In the fourth quarter of 2023, we realigned our reportable segments to better support our operational strategies. As a result, a portion of the Pacific segment’s businesses are now reported under the Energy Services segment. In addition, the North Central and South operating regions have been aggregated into one reportable segment, Central. We also reallocated certain amounts to the operating segments that were previously reported within Corporate Services. All periods have been recast to conform with the revised presentation. See Note 14 for additional information. Separation from MDU Resources On May 31, 2023, MDU Resources completed the previously announced separation of Knife River through the distribution of approximately 90 percent of the outstanding shares of common stock, par value $.01 per share, of Knife River to the stockholders of record of MDU Resources as of the close of business on May 22, 2023. MDU Resources retained approximately 10 percent of the outstanding shares of Knife River common stock. The Distribution was structured as a pro rata distribution of one share of Knife River common stock for every four shares of MDU Resources common stock. In November 2023, MDU Resources disposed of all 5,656,621 retained shares of Knife River common stock in an underwritten public offering. As a result of the Distribution, Knife River is now an independent public company and its common stock is listed under the symbol “KNF” on the New York Stock Exchange. All share and earnings per share information has been retroactively adjusted for all periods presented to reflect the Distribution.

v3.24.2.u1

Basis of presentation	6 Months Ended
	Jun. 30, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of presentation	Basis of presentation The accompanying consolidated interim financial statements were prepared in accordance with accounting principles generally accepted in the United States of America ("GAAP") for interim financial information and with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X. Interim financial statements do not include all disclosures provided in annual financial statements and, accordingly, these financial statements should be read in conjunction with the Company's 2023 Annual Report on Form 10-K ("Annual Report"). The information is unaudited but includes adjustments that are, in the opinion of management, necessary for a fair presentation of the accompanying consolidated interim financial statements and are of a normal recurring nature. Prior to the Separation, Knife River operated as a wholly owned subsidiary of Centennial Energy Holdings, Inc., a direct wholly owned subsidiary of MDU Resources and the direct parent company of Knife River prior to the spinoff ("Centennial") and an indirect, wholly owned subsidiary of MDU Resources and not as a stand-alone company. The accompanying consolidated financial statements and footnotes for the periods prior to the Separation were prepared on a "carve-out" basis using a legal entity approach in conformity with GAAP and were derived from the consolidated financial statements of MDU Resources as if Knife River operated on a stand-alone basis during these periods. All revenues and costs, as well as assets and liabilities, directly associated with our business activities are included in the consolidated financial statements. In the periods prior to the Separation, the consolidated financial statements include expense allocations for certain functions provided by MDU Resources and Centennial, including, but not limited to, certain general corporate expenses related to senior management, legal, human resources, finance and accounting, treasury, information technology, communications, procurement, tax, insurance and other shared services. These general corporate expenses are included in the Consolidated Statements of Operations within selling, general and administrative expenses and other income. For the three and six months ended June 30, 2023, the amount allocated to Knife River was $4.7 million and $9.6 million, respectively, in selling, general and administrative expenses and $300,000 and $600,000, respectively, in other income. These items were allocated on the basis of direct usage when identifiable, with the remainder principally allocated on the basis of percent of total capital invested or other allocation methodologies that were considered to be a reasonable reflection of the utilization of the services provided to the benefits received, including the following: number of employees paid and stated as cost per check; number of employees served; weighted factor of travel, managed units, national account spending, equipment and fleet acquisitions; purchase order dollars spent and purchase order line count; number of payments, vouchers or unclaimed property reports; labor hours; time tracked; and projected workload. The allocations may not, however, reflect the expenses we would have incurred as a stand-alone company for the periods presented. These costs also may not be indicative of the expenses that we will incur in the future or would have incurred if we had obtained these services from a third party. Management has also evaluated the impact of events occurring after June 30, 2024, up to the date of issuance of these consolidated interim financial statements on August 6, 2024, that would require recognition or disclosure in the Consolidated Financial Statements. Principles of consolidation For all periods, the consolidated financial statements were prepared in accordance with GAAP and include the accounts of Knife River and its wholly owned subsidiaries. All intercompany accounts and transactions between the businesses comprising Knife River have been eliminated in the accompanying audited consolidated financial statements. Use of estimates The preparation of financial statements in conformity with GAAP requires us to make estimates and assumptions that affect the reported amounts of assets and liabilities, and disclosure of contingent assets and liabilities, at the date of the consolidated financial statements, as well as the reported amounts of revenues and expenses during the reporting period. Estimates are used for items such as long-lived assets and goodwill; fair values of acquired assets and liabilities under the acquisition method of accounting; aggregate reserves; property depreciable lives; tax provisions; revenue recognized using the cost-to-cost measure of progress for contracts; expected credit losses; environmental and other loss contingencies; costs on contracting services contracts; actuarially determined benefit costs; asset retirement obligations; lease classification; present value of right-of-use assets and lease liabilities; and the valuation of stock-based compensation. These estimates are based on management’s best knowledge of current events, historical experience, actions that we may undertake in the future and on various other assumptions that are believed to be reasonable under the circumstances. As additional information becomes available, or actual amounts are determinable, the recorded estimates are revised. Consequently, operating results can be affected by revisions to prior accounting estimates. Cash, cash equivalents and restricted cash We consider all highly liquid investments with an original maturity of three months or less, when purchased, to be cash and cash equivalents. Restricted cash represents deposits held by our captive insurance company that is required by state insurance regulations to remain in the captive insurance company. Cash, cash equivalents and restricted cash on the Consolidated Balance Sheets is comprised of: June 30, 2024 June 30, 2023 December 31, 2023 (In thousands) Cash and cash equivalents $ 15,468 $ 40,089 $ 219,324 Restricted cash 41,701 28,400 42,996 Cash, cash equivalents and restricted cash $ 57,169 $ 68,489 $ 262,320 Seasonality of operations Some of our operations are seasonal and revenues from, and certain expenses for, such operations may fluctuate significantly among quarterly periods, with lower activity in the winter months and higher activity in the summer months. Accordingly, the interim results for particular segments, and for Knife River as a whole, may not be indicative of results for the full fiscal year or other future periods.

v3.24.2.u1

New accounting standards	6 Months Ended
	Jun. 30, 2024
Accounting Policies [Abstract]
New accounting standards	New accounting standards The following table provides a brief description of the accounting pronouncements applicable to Knife River and the potential impact on its consolidated financial statements and/or disclosures: Standard Description Standard Effective Date Impact on financial statements/disclosures Recently issued Financial Accounting Standards Board (FASB) accounting standards updates ("ASU") not yet adopted ASU 2023-07 - Improvements to Reportable Segment Disclosures In November 2023, the FASB issued guidance on modifying the disclosure requirements to improve reportable segment disclosure requirements through enhanced disclosures about significant segment expenses. The guidance also expands the interim disclosure requirements. The guidance is to be applied on a retrospective basis to the financial statements and footnotes and early adoption is permitted. Fiscal periods beginning after December 15, 2023 and interim periods beginning after December 31, 2024 The Company is currently evaluating the impact the guidance will have on its disclosures for the year ended December 31, 2024 and interim periods for fiscal year 2025. ASU 2023-09 - Improvements to Income Tax Disclosures In December 2023, the FASB issued guidance on modifying the disclosure requirements to increase transparency about income tax information through improvements to income tax disclosures primarily related to the rate reconciliation and income taxes paid information. The guidance is to be applied on a prospective basis to the financial statements and footnotes, however, retrospective adoption is also permitted. The guidance also permits early adoption. Fiscal periods beginning after December 15, 2024 The Company is currently evaluating the impact the guidance will have on its disclosures for the year ended December 31, 2025.

v3.24.2.u1

Receivables and allowance for expected credit losses	6 Months Ended
	Jun. 30, 2024
Credit Loss [Abstract]
Receivables and allowance for expected credit loss	Receivables and allowance for expected credit losses Receivables consist primarily of trade and contract receivables for the sale of goods and services net of expected credit losses. A majority of our receivables are due in 30 days or less. The total balance of receivables past due 90 days or more was $7.4 million, $11.6 million and $16.7 million at June 30, 2024, June 30, 2023 and December 31, 2023, respectively. Receivables were as follows: June 30, 2024 June 30, 2023 December 31, 2023 (In thousands) Trade receivables $ 206,673 $ 220,948 $ 124,134 Contract receivables 188,120 173,318 112,037 Retention receivables 32,649 30,224 36,782 Receivables, gross 427,442 424,490 272,953 Less expected credit loss 4,501 5,870 6,168 Receivables, net $ 422,941 $ 418,620 $ 266,785 The Company's expected credit losses are determined through a review using historical credit loss experience; changes in asset specific characteristics; current conditions; and reasonable and supportable future forecasts, among other specific account data, and is performed at least quarterly. We develop and document our methodology to determine our allowance for expected credit losses. Risk characteristics used by management may include customer mix, knowledge of customers and general economic conditions of the various local economies, among others. Specific account balances are written off when management determines the amounts to be uncollectible. Management has reviewed the balance reserved through the allowance for expected credit losses and believes it is reasonable. Details of the Company's expected credit losses were as follows: Pacific Northwest Mountain Central Energy Services Total   (In thousands) As of December 31, 2023 $ 2,053  $ 1,004  $ 2,293  $ 718  $ 100  $ 6,168  Current expected credit loss provision 177  (223) (47) 87  —  (6) Less write-offs charged against the allowance (53) 133  2  3  —  85  At March 31, 2024 $ 2,283  $ 648  $ 2,244  $ 802  $ 100  $ 6,077  Current expected credit loss provision 25  79  27  151  1  283  Less write-offs charged against the allowance 513  11  1,122  212  1  1,859  At June 30, 2024 $ 1,795  $ 716  $ 1,149  $ 741  $ 100  $ 4,501  Pacific Northwest Mountain Central Energy Services Total   (In thousands) As of December 31, 2022 $ 1,945  $ 1,253  $ 1,278  $ 901  $ 100  $ 5,477  Current expected credit loss provision 45  313  164  (90) —  432  Less write-offs charged against the allowance 1  68  18  —  —  87  At March 31, 2023 $ 1,989  $ 1,498  $ 1,424  $ 811  $ 100  $ 5,822  Current expected credit loss provision 8  74  631  (131) 1  583  Less write-offs charged against the allowance 17  512  3  2  1  535  At June 30, 2023 $ 1,980  $ 1,060  $ 2,052  $ 678  $ 100  $ 5,870

v3.24.2.u1

Inventories	6 Months Ended
	Jun. 30, 2024
Inventory Disclosure [Abstract]
Inventories	Inventories Inventories on the Consolidated Balance Sheets were as follows:   June 30, 2024 June 30, 2023 December 31, 2023   (In thousands) Finished products $ 245,983  $ 227,683  $ 225,319  Raw materials 100,029  104,689  61,776  Supplies and parts 39,366  42,005  32,528  Total $ 385,378  $ 374,377  $ 319,623  Inventories are valued at the lower of cost or net realizable value using the average cost method. Inventories include production costs incurred as part of our aggregate mining activities. These inventoriable production costs include all mining and processing costs associated with the production of aggregates. Stripping costs incurred during the production phase, which represent costs of removing overburden and waste materials to access mineral deposits, are a component of inventoriable production costs.

v3.24.2.u1

Net income per share	6 Months Ended
	Jun. 30, 2024
Earnings Per Share [Abstract]
Net income per share	Net income per share Basic net income per share is computed by dividing net income by the weighted average number of shares of common stock outstanding during the applicable period. Diluted net income per share is computed by dividing net income by the total of the weighted average number of shares of common stock outstanding during the applicable period, plus the effect of non-vested performance shares and restricted stock units. Weighted average common shares outstanding is comprised of issued shares of 57,043,841 less shares held in treasury of 431,136. Basic and diluted net income per share are calculated as follows, based on a reconciliation of the weighted-average common shares outstanding on a basic and diluted basis: Three Months Ended Six Months Ended June 30, June 30, 2024 2023 2024 2023 (In thousands, except per share amounts) Net income $ 77,929  $ 56,836  $ 30,301  $ 15,516  Weighted average common shares outstanding - basic 56,611  56,566  56,601  56,566  Effect of dilutive performance shares and restricted stock units 200  33  190  17  Weighted average common shares outstanding - diluted 56,811  56,599  56,791  56,583  Shares excluded from the calculation of diluted loss per share 16  —  21  —  Net income per share - basic $ 1.38  $ 1.00  $ .54  $ .27  Net income per share - diluted $ 1.37  $ 1.00  $ .53  $ .27

v3.24.2.u1

Accumulated other comprehensive loss	6 Months Ended
	Jun. 30, 2024
Equity [Abstract]
Accumulated other comprehensive loss	Accumulated other comprehensive loss The after-tax changes in the components of accumulated other comprehensive loss were as follows: Net Unrealized Loss on Derivative  Instruments  Qualifying as Hedges Postretirement  Liability Adjustment Total Accumulated  Other Comprehensive  Loss   (In thousands) As of December 31, 2023 $ —  $ (11,319) $ (11,319) Amounts reclassified from accumulated other comprehensive loss —  78  78  Net current-period other comprehensive income —  78  78  At March 31, 2024 $ —  $ (11,241) $ (11,241) Amounts reclassified from accumulated other comprehensive loss —  77  77  Net current-period other comprehensive income —  77  77  At June 30, 2024 $ —  $ (11,164) $ (11,164) Net Unrealized Loss on Derivative  Instruments  Qualifying as Hedges Postretirement  Liability Adjustment Total Accumulated  Other Comprehensive  Loss   (In thousands) As of December 31, 2022 $ (90) $ (12,262) $ (12,352) Amounts reclassified from accumulated other comprehensive loss 46  47  93  Net current-period other comprehensive income 46  47  93  At March 31, 2023 $ (44) $ (12,215) $ (12,259) Other comprehensive loss before reclassification —  (17) (17) Amounts reclassified from accumulated other comprehensive loss 44  48  92  Net current-period other comprehensive income 44  31  75  At June 30, 2023 $ —  $ (12,184) $ (12,184) The following amounts were reclassified out of accumulated other comprehensive loss into net income. The amounts presented in parenthesis indicate a decrease to net income on the Consolidated Statements of Operations. The reclassifications were as follows: Three Months Ended Six Months Ended Location on Consolidated Statements of Operations June 30, June 30, 2024 2023 2024 2023 (In thousands) Reclassification adjustment for loss on derivative instruments included in net income $ —  $ (57) $ —  $ (118) Interest expense —  13  —  28  Income taxes —  (44) —  (90) Amortization of postretirement liability losses included in net periodic benefit cost (102) (63) (205) (126) Other income 25  15  50  31  Income taxes (77) (48) (155) (95) Total reclassifications $ (77) $ (92) $ (155) $ (185)

v3.24.2.u1

Revenue from contracts with customers	6 Months Ended
	Jun. 30, 2024
Revenue from Contract with Customer [Abstract]
Revenue from contracts with customers	Revenue from contracts with customers Revenue is recognized when a performance obligation is satisfied by transferring control over a product or service to a customer. Revenue includes revenue from the sales of construction materials and contracting services. Revenue is measured based on consideration specified in a contract with a customer and excludes any sales incentives and amounts collected on behalf of third parties. Knife River is considered an agent for certain taxes collected from customers. As such, we present revenues net of these taxes at the time of sale to be remitted to governmental authorities, including sales and use taxes. Revenue for construction materials is recognized at a point in time when delivery of the products has taken place. Contracting revenue is recognized over time using an input method based on the cost-to-cost measure of progress on a project. Disaggregation In the following tables, revenue is disaggregated by category for each segment and includes sales of materials to both third parties and internal customers. Due to consolidation requirements, the internal sales revenues must be eliminated against the construction materials product used in downstream materials and contracting services to arrive at the external operating revenues. We believe this level of disaggregation best depicts how the nature, amount, timing and uncertainty of revenue and cash flows are affected by economic factors. For more information on the Company’s reportable segments, see Note 14. Three Months Ended June 30, 2024 Pacific Northwest Mountain Central Energy Services Corporate Services and Eliminations Total (In thousands) Aggregates $ 31,259  $ 53,061  $ 31,138  $ 42,943  $ —  $ —  $ 158,401  Ready-mix concrete 36,667  45,660  34,967  62,225  —  —  179,519  Asphalt 8,622  32,529  32,860  45,268  —  —  119,279  Liquid asphalt —  —  —  —  65,304  —  65,304  Other 42,357  5,574  7  10,875  14,386  4,511  77,710  Contracting services public-sector 20,713  71,299  90,023  102,820  —  —  284,855  Contracting services private-sector 14,222  25,596  41,552  5,549  —  —  86,919  Internal sales (22,013) (33,494) (36,778) (55,077) (13,447) (4,272) (165,081) Revenues from contracts with customers $ 131,827  $ 200,225  $ 193,769  $ 214,603  $ 66,243  $ 239  $ 806,906  Three Months Ended June 30, 2023 Pacific Northwest Mountain Central Energy Services Corporate Services and Eliminations Total (In thousands) Aggregates $ 27,446  $ 47,966  $ 28,866  $ 42,138  $ —  $ —  $ 146,416  Ready-mix concrete 40,526  44,583  34,506  65,283  —  —  184,898  Asphalt 6,275  34,518  29,472  54,672  —  —  124,937  Liquid asphalt —  —  —  —  72,920  —  72,920  Other 39,802  4,335  8  10,909  13,849  1,341  70,244  Contracting services public-sector 16,848  53,301  80,381  114,025  —  —  264,555  Contracting services private-sector 16,575  29,353  37,317  5,637  —  —  88,882  Internal sales (22,393) (35,322) (34,796) (61,630) (13,706) 184  (167,663) Revenues from contracts with customers $ 125,079  $ 178,734  $ 175,754  $ 231,034  $ 73,063  $ 1,525  $ 785,189  Six Months Ended June 30, 2024 Pacific Northwest Mountain Central Energy Services Corporate Services and Eliminations Total (In thousands) Aggregates $ 50,809  $ 92,459  $ 40,592  $ 58,814  $ —  $ —  $ 242,674  Ready-mix concrete 67,887  77,436  48,803  85,248  —  —  279,374  Asphalt 10,969  40,766  33,690  50,326  —  —  135,751  Liquid asphalt —  —  —  —  76,340  —  76,340  Other 67,686  9,147  13  12,773  17,448  9,654  116,721  Contracting services public-sector 26,188  107,343  115,882  123,853  —  —  373,266  Contracting services private-sector 22,296  40,628  55,355  5,724  —  —  124,003  Internal sales (35,621) (48,402) (40,740) (61,173) (16,428) (9,269) (211,633) Revenues from contracts with customers $ 210,214  $ 319,377  $ 253,595  $ 275,565  $ 77,360  $ 385  $ 1,136,496  Six Months Ended June 30, 2023 Pacific Northwest Mountain Central Energy Services Corporate Services and Eliminations Total (In thousands) Aggregates $ 46,143  $ 90,540  $ 38,532  $ 54,722  $ —  $ —  $ 229,937  Ready-mix concrete 66,670  78,488  48,876  87,633  —  —  281,667  Asphalt 7,591  41,445  30,282  59,238  —  —  138,556  Liquid asphalt —  —  —  —  81,206  —  81,206  Other 63,222  7,016  11  12,495  16,040  1,767  100,551  Contracting services public-sector 20,819  70,304  108,619  136,885  —  —  336,627  Contracting services private-sector 19,474  55,115  50,762  6,442  —  —  131,793  Internal sales (33,197) (48,254) (40,710) (68,761) (15,928) (398) (207,248) Revenues from contracts with customers $ 190,722  $ 294,654  $ 236,372  $ 288,654  $ 81,318  $ 1,369  $ 1,093,089

v3.24.2.u1

Uncompleted contracts	6 Months Ended
	Jun. 30, 2024
Revenue from Contract with Customer [Abstract]
Uncompleted contracts	Uncompleted contracts The timing of revenue recognition may differ from the timing of invoicing to customers. The timing of invoicing to customers does not necessarily correlate with the timing of revenues being recognized under the cost-to-cost method of accounting. Contracts from contracting services are billed as work progresses in accordance with agreed upon contractual terms. Generally, billing to the customer occurs contemporaneous to revenue recognition. A variance in timing of the billings may result in a contract asset or a contract liability. A contract asset occurs when revenues are recognized under the cost-to-cost measure of progress, which exceeds amounts billed on uncompleted contracts. Such amounts will be billed as standard contract terms allow, usually based on various measures of performance or achievement. A contract liability occurs when there are billings in excess of revenues recognized under the cost-to-cost measure of progress on uncompleted contracts. Contract liabilities decrease as revenue is recognized from the satisfaction of the related performance obligation. The changes in contract assets and liabilities were as follows: June 30, 2024 December 31, 2023 Change Location on Consolidated Balance Sheets (In thousands) Contract assets $ 49,150  $ 27,293  $ 21,857  Costs and estimated earnings in excess of billings on uncompleted contracts Contract liabilities (45,123) (51,376) 6,253  Billings in excess of costs and estimated earnings on uncompleted contracts Net contract assets (liabilities) $ 4,027  $ (24,083) $ 28,110  June 30, 2023 December 31, 2022 Change Location on Consolidated Balance Sheets (In thousands) Contract assets $ 58,020  $ 31,145  $ 26,875  Costs and estimated earnings in excess of billings on uncompleted contracts Contract liabilities (44,590) (39,843) (4,747) Billings in excess of costs and estimated earnings on uncompleted contracts Net contract assets (liabilities) $ 13,430  $ (8,698) $ 22,128  The Company recognized $14.4 million and $44.9 million in revenue for the three and six months ended June 30, 2024, respectively, which was previously included in contract liabilities at December 31, 2023. The Company recognized $11.4 million and $31.7 million in revenue for the three and six months ended June 30, 2023, respectively, which was previously included in contract liabilities at December 31, 2022. The Company recognized a net increase in revenues of $15.1 million and $21.2 million for the three and six months ended June 30, 2024, respectively, from performance obligations satisfied in prior periods. The Company recognized a net increase in revenues of $7.4 million and $8.1 million for the three and six months ended June 30, 2023, respectively, from performance obligations satisfied in prior periods. Remaining performance obligations The remaining performance obligations, also referred to as backlog, include unrecognized revenues that we reasonably expect to be realized. These unrecognized revenues can include: projects that have a written award, a letter of intent, a notice to proceed, an agreed upon work order to perform work on mutually accepted terms and conditions, and change orders or claims to the extent management believes additional contract revenues will be earned and are deemed probable of collection. The majority of our contracts for contracting services have an original duration of less than one year. At June 30, 2024, the Company's remaining performance obligations were $988.5 million. We expect to recognize the following revenue amounts in future periods related to these remaining performance obligations: $936.7 million within the next 12 months or less; $44.0 million within the next 13 to 24 months; and $7.8 million in 25 months or more.

v3.24.2.u1

Goodwill and other intangible assets	6 Months Ended
	Jun. 30, 2024
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and other intangible assets	Goodwill and other intangible assets The changes in the carrying amount of goodwill were as follows: Balance at January 1, 2024 Goodwill Acquired During the Year Measurement Period Adjustments Reallocation of Goodwill Balance at June 30, 2024   (In thousands) Pacific $ 32,621  $ —  $ —  $ —  $ 32,621  Northwest 90,978  —  —  —  90,978  Mountain 26,816  —  —  —  26,816  North Central 75,879  735  —  —  76,614  South 38,708  —  —  —  38,708  Energy Services 9,476  —  —  —  9,476  Total $ 274,478  $ 735  $ —  $ —  $ 275,213  Balance at January 1, 2023 Goodwill Acquired During the Year Measurement Period Adjustments Reallocation of Goodwill Balance at June 30, 2023   (In thousands) Pacific $ 38,339  $ —  $ (62) $ —  $ 38,277  Northwest 90,978  —  —  —  90,978  Mountain 26,816  —  —  —  26,816  North Central 75,879  —  —  —  75,879  South 38,708  —  —  —  38,708  Energy Services 3,820  —  —  —  3,820  Total $ 274,540  $ —  $ (62) $ —  $ 274,478  Balance at January 1, 2023 Goodwill Acquired During the Year Measurement Period Adjustments Reallocation of Goodwill Balance at December 31, 2023   (In thousands) Pacific $ 38,339  $ —  $ (62) $ (5,656) $ 32,621  Northwest 90,978  —  —  —  90,978  Mountain 26,816  —  —  —  26,816  North Central 75,879  —  —  —  75,879  South 38,708  —  —  —  38,708  Energy Services 3,820  —  —  5,656  9,476  Total $ 274,540  $ —  $ (62) $ —  $ 274,478  Other amortizable intangible assets were as follows:   June 30, 2024 June 30, 2023 December 31, 2023   (In thousands) Customer relationships $ 18,868  $ 18,540  $ 18,540  Less accumulated amortization 9,977  8,235  9,102    8,891  10,305  9,438  Noncompete agreements 3,784  4,039  4,039  Less accumulated amortization 3,283  3,239  3,473  501  800  566  Other 1,796  2,479  2,479  Less accumulated amortization 1,044  1,474  1,662    752  1,005  817  Total $ 10,144  $ 12,110  $ 10,821  Amortization expense for amortizable intangible assets for the three and six months ended June 30, 2024, was $526,000 and $1.1 million, respectively. Amortization expense for amortizable intangible assets for the three and six months ended June 30, 2023, was $653,000 and $1.3 million, respectively. Estimated amortization expense for identifiable intangible assets as of June 30, 2024, was: Remainder of 2024 2025 2026 2027 2028 Thereafter (In thousands) Amortization expense $ 1,192  $ 1,964  $ 1,784  $ 1,761  $ 1,717  $ 1,726

v3.24.2.u1

Fair value measurements	6 Months Ended
	Jun. 30, 2024
Fair Value Disclosures [Abstract]
Fair value measurements	Fair value measurements Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability (an exit price) in an orderly transaction between market participants at the measurement date. The fair value guidance establishes a hierarchy for grouping assets and liabilities, based on the significance of inputs. The estimated fair values of the Company's assets and liabilities measured on a recurring basis are determined using the market approach. Financial instruments measured at fair value on a recurring basis We measure our investments in certain fixed-income and equity securities at fair value with changes in fair value recognized in income. We anticipate using these investments, which consist of insurance contracts, to satisfy our obligations under our unfunded, nonqualified defined benefit and defined contribution plans for our executive officers and certain key management employees, and invests in these fixed-income and equity securities for the purpose of earning investment returns and capital appreciation. These investments, which totaled $27.3 million, $19.1 million and $24.9 million at June 30, 2024 and 2023, and December 31, 2023, respectively, are classified as investments on the Consolidated Balance Sheets. The net unrealized gains on these investments were $392,000 and $197,000 for the three months ended and $1.6 million and $1.1 million for the six months ended June 30, 2024 and 2023, respectively. The change in fair value, which is considered part of the cost of the plan, is classified in other income on the Consolidated Statements of Operations. The Company's assets measured at fair value on a recurring basis were as follows:   Fair Value Measurements at June 30, 2024, Using     Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Balance at June 30, 2024 (In thousands) Assets:         Money market funds $ —  $ 3,982  $ —  $ 3,982  Insurance contracts* —  27,289  —  27,289  Total assets measured at fair value $ —  $ 31,271  $ —  $ 31,271  *    The insurance contracts invest approximately 36 percent in fixed-income investments, 23 percent in common stock of large-cap companies, 15 percent in cash equivalents, 9 percent in common stock of mid-cap companies, 9 percent target date investments, 5 percent in common stock of small-cap companies, 1 percent in international investments, 1 percent in real estate investments and 1 percent in high yield investments.   Fair Value Measurements at June 30, 2023, Using     Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Balance at June 30, 2023 (In thousands) Assets:         Money market funds $ —  $ 7,529  $ —  $ 7,529  Insurance contracts* —  19,141  —  19,141  Total assets measured at fair value $ —  $ 26,670  $ —  $ 26,670  *    The insurance contracts invest approximately 47 percent in fixed-income investments, 20 percent in cash equivalents, 15 percent in common stock of large-cap companies, 8 percent in common stock of mid-cap companies, 6 percent in common stock of small-cap companies and 4 percent target date investments.   Fair Value Measurements at December 31, 2023, Using   Quoted Prices in Active Markets for Identical Assets  (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs  (Level 3) Balance at December 31, 2023 (In thousands) Assets:         Money market funds $ —  $ 3,241  $ —  $ 3,241  Insurance contracts* —  24,896  —  24,896  Total assets measured at fair value $ —  $ 28,137  $ —  $ 28,137  *    The insurance contracts invest approximately 40 percent in fixed-income investments, 19 percent in common stock of large-cap companies, 18 percent in cash equivalents, 8 percent in target date investments, 8 percent in common stock of mid-cap companies, 6 percent in common stock of small-cap companies and 1 percent in international investments. The Company’s Level 2 money market funds are valued at the net asset value of shares held at the end of the period, based on published market quotations on active markets, or using other known sources including pricing from outside sources. The estimated fair value of the Company’s Level 2 insurance contracts is based on contractual cash surrender values that are determined primarily by investments in managed separate accounts of the insurer. These amounts approximate fair value. The managed separate accounts are valued based on other observable inputs or corroborated market data. Though we believe the methods used to estimate fair value are consistent with those used by other market participants, the use of other methods or assumptions could result in a different estimate of fair value. Nonfinancial instruments measured at fair value on a nonrecurring basis We apply the provisions of the fair value measurement standard to our nonrecurring, non-financial measurements, including long-lived asset impairments. These assets are not measured at fair value on an ongoing basis but are subject to fair value adjustments only in certain circumstances. We review the carrying value of our long-lived assets, excluding goodwill, whenever events or changes in circumstances indicate that such carrying amounts may not be recoverable. The assets and liabilities of the acquisitions that occurred during the second quarter of 2024 were calculated using a market or cost approach. The fair value of some of the assets was determined based on Level 3 inputs including estimated future cash flows, discount rates, growth rates and sales projections, all of which require significant management judgment. The Company's long-term debt is not measured at fair value on the Consolidated Balance Sheets and the fair value is being provided for disclosure purposes only. The fair value was categorized as Level 2 in the fair value hierarchy and was based on discounted cash flows using current market interest rates. The estimated fair value of the Company's Level 2 long-term debt was as follows:   June 30, 2024 June 30, 2023 December 31, 2023   (In thousands) Carrying amount $ 693,483  $ 855,000  $ 696,985  Fair value $ 712,852  $ 862,420  $ 725,086  The carrying amounts of our remaining financial instruments included in current assets and current liabilities approximate their fair values.

v3.24.2.u1

Debt	6 Months Ended
	Jun. 30, 2024
Debt Disclosure [Abstract]
Debt	Debt Certain debt instruments of the Company contain restrictive covenants and cross-default provisions. In order to borrow under the debt agreements, we must be in compliance with the applicable covenants and certain other conditions, all of which the Company, as applicable, was in compliance with at June 30, 2024. In the event we do not comply with the applicable covenants and other conditions, alternative sources of funding may need to be pursued. Long-term Debt Outstanding Long-term debt outstanding was as follows:   Weighted Average Interest Rate at June 30, 2024 June 30, 2024 June 30, 2023 December 31, 2023   (In thousands) Term loan agreement due on May 31, 2028 7.20  % $ 268,125  $ 275,000  $ 271,562  Revolving credit agreement —  % —  155,000  —  Senior notes due on May 1, 2031 7.75  % 425,000  425,000  425,000  Other notes due on January 1, 2061 —  % 358  511  423  Less unamortized debt issuance costs 13,945  16,382  15,326  Total long-term debt 679,538  839,129  681,659  Less current maturities 7,072  7,082  7,082  Net long-term debt $ 672,466  $ 832,047  $ 674,577  Schedule of Debt Maturities Long-term debt maturities, which excludes unamortized debt issuance costs, at June 30, 2024, were as follows: Remainder of 2024 2025 2026 2027 2028 Thereafter (In thousands) Long-term debt maturities $ 3,634  $ 10,473  $ 13,750  $ 17,188  $ 223,438  $ 425,000

v3.24.2.u1

Cash flow information	6 Months Ended
	Jun. 30, 2024
Supplemental Cash Flow Information [Abstract]
Cash flow information	Cash flow information Cash expenditures for interest and income taxes were as follows: Six Months Ended   June 30,   2024 2023    (In thousands) Interest paid, net $ 27,993  $ 24,802  Income taxes paid, net $ 1,662  $ 558  Noncash investing and financing transactions were as follows: Six Months Ended June 30, 2024 2023  (In thousands) Right-of-use assets obtained in exchange for new operating lease liabilities $ 10,844  $ 7,552  Property, plant and equipment additions in accounts payable $ 5,098  $ 3,359  Equity contribution from Centennial related to the Separation $ —  $ 64,724  Equity contribution to MDU Resources for asset/liability transfers related to the Separation $ —  $ (1,548) MDU Resources' stock issued prior to spin in connection with a business combination $ —  $ 383

v3.24.2.u1

Business segment data	6 Months Ended
	Jun. 30, 2024
Segment Reporting [Abstract]
Business segment data	Business segment data We focus on the vertical integration of our products and services by offering customers a single source for construction materials and related contracting services. We operate in 14 states across the United States through our operating segments: Pacific, Northwest, Mountain, North Central, South and Energy Services. These operating segments are used to determine the Company’s reportable segments, Pacific, Northwest, Mountain, Central and Energy Services, which are based on our method of internal reporting and management of our business. Four of the reportable segments are aligned by key geographic areas due to the production of construction materials and related contracting services and one is based on product line. Each segment is led by a segment manager who reports to the Company’s chief operating officer, who is also the Company's chief operating decision maker, along with the chief executive officer. The chief operating decision maker evaluates the performance of the segments and allocates resources to them based on earnings before interest, taxes, depreciation, depletion and amortization ("EBITDA"). In the fourth quarter of 2023, we realigned our reportable segments to better support our operational strategies. The liquid asphalt and related services portion of the Pacific segment's businesses are now reported under the Energy Services segment. In addition, the North Central and South operating regions have been aggregated into one reportable segment, Central. We also reallocated certain amounts to the operating segments that were previously reported within Corporate Services. All periods have been recast to conform with the revised presentation. Each geographic segment offers a vertically integrated suite of products and services, including aggregates, ready-mix concrete, asphalt and contracting services, while the Energy Services segment produces and supplies liquid asphalt, primarily for use in asphalt road construction, and is a supplier to some of the other segments. Each geographic segment mines, processes and sells construction aggregates (crushed stone and sand and gravel); produces and sells asphalt; and produces and sells ready-mix concrete as well as vertically integrating its contracting services to support the aggregate-based product lines. Contracting services include heavy-civil construction, asphalt and concrete paving, and site development and grading. Although not common to all locations, the geographic segments also sell cement, merchandise and other building materials and related services. Corporate Services represents the unallocated costs of certain corporate functions, such as accounting, legal, treasury, information technology, human resources and other corporate expenses that support the operating segments. We account for intersegment sales and transfers as if the sales or transfers were to third parties. The accounting policies applicable to each segment are consistent with those used in the audited consolidated financial statements. The information below follows the same accounting policies as described in the audited financial statements and notes included in the Company's 2023 Annual Report. Information on the Company's segments was as follows: Three Months Ended Six Months Ended June 30, June 30,   2024  2023  2024  2023    (In thousands) External operating revenues:       Pacific $ 131,827  $ 125,079  $ 210,214  $ 190,722  Northwest 200,225  178,734  319,377  294,654  Mountain 193,769  175,754  253,595  236,372  Central 214,603  231,034  275,565  288,654  Energy Services 66,243  73,063  77,360  81,318  Total reportable segment external operating revenues $ 806,667  $ 783,664  $ 1,136,111  $ 1,091,720  Intersegment operating revenues: Pacific $ 22,013  $ 22,393  $ 35,621  $ 33,197  Northwest 33,494  35,322  48,402  48,254  Mountain 36,778  34,796  40,740  40,710  Central 55,077  61,630  61,173  68,761  Energy Services 13,447  13,706  16,428  15,928  Total reportable segment intersegment operating revenues $ 160,809  $ 167,847  $ 202,364  $ 206,850  EBITDA:         Pacific $ 17,789  $ 17,457  $ 17,046  $ 17,605  Northwest 50,762  38,871  70,916  52,868  Mountain 43,119  30,323  37,054  26,570  Central 36,188  28,399  17,466  11,500  Energy Services 19,367  21,781  16,884  18,804  Total reportable segment EBITDA $ 167,225  $ 136,831  $ 159,366  $ 127,347  A reconciliation of consolidated operating revenues to reportable segment operating revenues is as follows: Three Months Ended Six Months Ended June 30, June 30, 2024 2023 2024 2023 (In thousands) Consolidated operating revenues $ 806,906  $ 785,189  $ 1,136,496  $ 1,093,089  Plus: Intersegment operating revenues 165,081  167,663  211,633  207,248  Less: Corporate Services revenue 4,511  1,341  9,654  1,767  Total reportable segment operating revenues $ 967,476  $ 951,511  $ 1,338,475  $ 1,298,570  A reconciliation of consolidated net income before income taxes to reportable segment EBITDA is as follows: Three Months Ended Six Months Ended June 30, June 30, 2024 2023 2024 2023 (In thousands) Total consolidated net income before income taxes $ 104,114  $ 76,855  $ 40,160  $ 23,623  Plus: Depreciation, depletion and amortization 34,512  31,130  66,724  60,760  Interest expense, net* 12,809  17,130  23,955  26,625  Less: Corporate Services EBITDA (15,790) (11,716) (28,527) (16,339) Total EBITDA for reportable segments $ 167,225  $ 136,831  $ 159,366  $ 127,347  *Interest, net is interest expense net of interest income.

v3.24.2.u1

Commitments and contingencies	6 Months Ended
	Jun. 30, 2024
Commitments and Contingencies Disclosure [Abstract]
Commitments and contingencies	Commitments and contingencies The Company is party to claims and lawsuits arising out of its business and that of its consolidated subsidiaries, which may include, but are not limited to, matters involving property damage, personal injury, and environmental, contractual and statutory obligations. We accrue a liability for those contingencies when the incurrence of a loss is probable and the amount can be reasonably estimated. If a range of amounts can be reasonably estimated and no amount within the range is a better estimate than any other amount, then the minimum of the range is accrued. We do not accrue liabilities when the likelihood that the liability has been incurred is probable but the amount cannot be reasonably estimated or when the liability is believed to be only reasonably possible or remote. For contingencies where an unfavorable outcome is probable or reasonably possible and which are material, we disclose the nature of the contingency and, in some circumstances, an estimate of the possible loss. Accruals are based on the best information available, but in certain situations management is unable to estimate an amount or range of a reasonably possible loss including, but not limited to when: (1) the damages are unsubstantiated or indeterminate, (2) the proceedings are in the early stages, (3) numerous parties are involved, or (4) the matter involves novel or unsettled legal theories. At June 30, 2024 and 2023, and December 31, 2023, we accrued contingent liabilities as a result of litigation, which have not been discounted, of $3.2 million, $970,000 and $873,000, respectively. At June 30, 2024 and 2023 and December 31, 2023, we also recorded corresponding insurance receivables of $0, $325,000 and $42,000, respectively, related to the accrued liabilities. Most of these claims and lawsuits are covered by insurance, thus the Company's exposure is typically limited to its deductible amount. Management will continue to monitor each matter and adjust accruals as might be warranted based on new information and further developments. Management believes that the outcomes with respect to probable and reasonably possible losses in excess of the amounts accrued, net of insurance recoveries, while uncertain, either cannot be estimated or will not have a material effect upon the Company's financial position, results of operations or cash flows. Unless otherwise required by GAAP, legal costs are expensed as they are incurred. Environmental matters The Company is a party to claims for the cleanup of a superfund site in Portland, Oregon. There were no material changes to the environmental matters that were previously reported in the audited financial statements and notes included in the Company's 2023 Annual Report. Guarantees Knife River and certain of its subsidiaries have outstanding obligations to third parties where the Company has guaranteed their performance. These guarantees are related to contracts for contracting services and certain other guarantees. At June 30, 2024, the fixed maximum amounts guaranteed under these agreements aggregated to $11.5 million, all of which have no scheduled maturity date. Certain of the guarantees also have no fixed maximum amounts specified. There were no amounts outstanding under the previously mentioned guarantees at June 30, 2024. Knife River and certain of its subsidiaries have outstanding letters of credit to third parties related to insurance policies, cement purchases and other agreements. At June 30, 2024, the fixed maximum amounts guaranteed under these letters of credit aggregated $20.9 million. At June 30, 2024, the amounts of scheduled expiration of the maximum amounts guaranteed under these letters of credit aggregate to $335,000 in 2024, $20.5 million in 2025, $0 in 2026 and $104,000 in 2027. There were no amounts outstanding under the previously mentioned letters of credit at June 30, 2024. In the normal course of business, we have surety bonds related to contracts for contracting services, reclamation obligations and insurance policies of its subsidiaries. In the event a subsidiary of Knife River does not fulfill a bonded obligation, the Company would be responsible to the surety bond company for completion of the bonded contract or obligation. A large portion of the surety bonds are expected to expire within the next 12 months; however, we will likely continue to enter into surety bonds for our subsidiaries in the future. At June 30, 2024, approximately $894.2 million of surety bonds were outstanding, which were not reflected on the Consolidated Balance Sheet.

v3.24.2.u1

Related party transactions	6 Months Ended
	Jun. 30, 2024
Related Party Transactions [Abstract]
Related party transactions	Related-party transactions Transition services agreements As part of the Separation, MDU Resources is providing transition services to Knife River and Knife River is providing transition services to MDU Resources in accordance with the Transition Services Agreement entered into on May 30, 2023. The Company paid $413,000 and $599,000 for the three months ended and $1.2 million and $599,000 for the six months ended June 30, 2024 and 2023, respectively, related to these activities, which were reflected in selling, general and administrative expenses on the Consolidated Statements of Operations. The Company received $62,000 and $277,000 for the three months ended and $138,000 and $277,000 for the six months ended June 30, 2024 and 2023, respectively, related to these activities, which were reflected in other income on the Consolidated Statements of Operations. The majority of the transition services were completed over a period of one year after the Separation. The Company expects minimal continued services by Knife River to MDU Resources through May 2025. For additional information on the presentation of related-party transactions, see Note 2.

v3.24.2.u1

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2024	Jun. 30, 2023
Pay vs Performance Disclosure
Net income (loss)	$ 77,929	$ (47,629)	$ 56,836	$ (41,320)	$ 30,301	$ 15,516

v3.24.2.u1

Insider Trading Arrangements	3 Months Ended
	Jun. 30, 2024
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

v3.24.2.u1

Basis of presentation (Policies)	6 Months Ended
	Jun. 30, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of presentation	The accompanying consolidated interim financial statements were prepared in accordance with accounting principles generally accepted in the United States of America ("GAAP") for interim financial information and with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X. Interim financial statements do not include all disclosures provided in annual financial statements and, accordingly, these financial statements should be read in conjunction with the Company's 2023 Annual Report on Form 10-K ("Annual Report"). The information is unaudited but includes adjustments that are, in the opinion of management, necessary for a fair presentation of the accompanying consolidated interim financial statements and are of a normal recurring nature. Prior to the Separation, Knife River operated as a wholly owned subsidiary of Centennial Energy Holdings, Inc., a direct wholly owned subsidiary of MDU Resources and the direct parent company of Knife River prior to the spinoff ("Centennial") and an indirect, wholly owned subsidiary of MDU Resources and not as a stand-alone company. The accompanying consolidated financial statements and footnotes for the periods prior to the Separation were prepared on a "carve-out" basis using a legal entity approach in conformity with GAAP and were derived from the consolidated financial statements of MDU Resources as if Knife River operated on a stand-alone basis during these periods. All revenues and costs, as well as assets and liabilities, directly associated with our business activities are included in the consolidated financial statements. In the periods prior to the Separation, the consolidated financial statements include expense allocations for certain functions provided by MDU Resources and Centennial, including, but not limited to, certain general corporate expenses related to senior management, legal, human resources, finance and accounting, treasury, information technology, communications, procurement, tax, insurance and other shared services. These general corporate expenses are included in the Consolidated Statements of Operations within selling, general and administrative expenses and other income. For the three and six months ended June 30, 2023, the amount allocated to Knife River was $4.7 million and $9.6 million, respectively, in selling, general and administrative expenses and $300,000 and $600,000, respectively, in other income. These items were allocated on the basis of direct usage when identifiable, with the remainder principally allocated on the basis of percent of total capital invested or other allocation methodologies that were considered to be a reasonable reflection of the utilization of the services provided to the benefits received, including the following: number of employees paid and stated as cost per check; number of employees served; weighted factor of travel, managed units, national account spending, equipment and fleet acquisitions; purchase order dollars spent and purchase order line count; number of payments, vouchers or unclaimed property reports; labor hours; time tracked; and projected workload. The allocations may not, however, reflect the expenses we would have incurred as a stand-alone company for the periods presented. These costs also may not be indicative of the expenses that we will incur in the future or would have incurred if we had obtained these services from a third party. Management has also evaluated the impact of events occurring after June 30, 2024, up to the date of issuance of these consolidated interim financial statements on August 6, 2024, that would require recognition or disclosure in the Consolidated Financial Statements.
Principles of consolidation	Principles of consolidation For all periods, the consolidated financial statements were prepared in accordance with GAAP and include the accounts of Knife River and its wholly owned subsidiaries. All intercompany accounts and transactions between the businesses comprising Knife River have been eliminated in the accompanying audited consolidated financial statements.
Use of estimates	Use of estimates The preparation of financial statements in conformity with GAAP requires us to make estimates and assumptions that affect the reported amounts of assets and liabilities, and disclosure of contingent assets and liabilities, at the date of the consolidated financial statements, as well as the reported amounts of revenues and expenses during the reporting period. Estimates are used for items such as long-lived assets and goodwill; fair values of acquired assets and liabilities under the acquisition method of accounting; aggregate reserves; property depreciable lives; tax provisions; revenue recognized using the cost-to-cost measure of progress for contracts; expected credit losses; environmental and other loss contingencies; costs on contracting services contracts; actuarially determined benefit costs; asset retirement obligations; lease classification; present value of right-of-use assets and lease liabilities; and the valuation of stock-based compensation. These estimates are based on management’s best knowledge of current events, historical experience, actions that we may undertake in the future and on various other assumptions that are believed to be reasonable under the circumstances. As additional information becomes available, or actual amounts are determinable, the recorded estimates are revised. Consequently, operating results can be affected by revisions to prior accounting estimates.
Cash, cash equivalents and restricted cash	Cash, cash equivalents and restricted cash We consider all highly liquid investments with an original maturity of three months or less, when purchased, to be cash and cash equivalents.
Seasonality of operations	Seasonality of operations Some of our operations are seasonal and revenues from, and certain expenses for, such operations may fluctuate significantly among quarterly periods, with lower activity in the winter months and higher activity in the summer months. Accordingly, the interim results for particular segments, and for Knife River as a whole, may not be indicative of results for the full fiscal year or other future periods.
New accounting standards	The following table provides a brief description of the accounting pronouncements applicable to Knife River and the potential impact on its consolidated financial statements and/or disclosures: Standard Description Standard Effective Date Impact on financial statements/disclosures Recently issued Financial Accounting Standards Board (FASB) accounting standards updates ("ASU") not yet adopted ASU 2023-07 - Improvements to Reportable Segment Disclosures In November 2023, the FASB issued guidance on modifying the disclosure requirements to improve reportable segment disclosure requirements through enhanced disclosures about significant segment expenses. The guidance also expands the interim disclosure requirements. The guidance is to be applied on a retrospective basis to the financial statements and footnotes and early adoption is permitted. Fiscal periods beginning after December 15, 2023 and interim periods beginning after December 31, 2024 The Company is currently evaluating the impact the guidance will have on its disclosures for the year ended December 31, 2024 and interim periods for fiscal year 2025. ASU 2023-09 - Improvements to Income Tax Disclosures In December 2023, the FASB issued guidance on modifying the disclosure requirements to increase transparency about income tax information through improvements to income tax disclosures primarily related to the rate reconciliation and income taxes paid information. The guidance is to be applied on a prospective basis to the financial statements and footnotes, however, retrospective adoption is also permitted. The guidance also permits early adoption. Fiscal periods beginning after December 15, 2024 The Company is currently evaluating the impact the guidance will have on its disclosures for the year ended December 31, 2025.
Expected credit loss	Receivables consist primarily of trade and contract receivables for the sale of goods and services net of expected credit losses. A majority of our receivables are due in 30 days or less.The Company's expected credit losses are determined through a review using historical credit loss experience; changes in asset specific characteristics; current conditions; and reasonable and supportable future forecasts, among other specific account data, and is performed at least quarterly. We develop and document our methodology to determine our allowance for expected credit losses. Risk characteristics used by management may include customer mix, knowledge of customers and general economic conditions of the various local economies, among others. Specific account balances are written off when management determines the amounts to be uncollectible.
Accounting Standards Update and Change in Accounting Principle	The following table provides a brief description of the accounting pronouncements applicable to Knife River and the potential impact on its consolidated financial statements and/or disclosures: Standard Description Standard Effective Date Impact on financial statements/disclosures Recently issued Financial Accounting Standards Board (FASB) accounting standards updates ("ASU") not yet adopted ASU 2023-07 - Improvements to Reportable Segment Disclosures In November 2023, the FASB issued guidance on modifying the disclosure requirements to improve reportable segment disclosure requirements through enhanced disclosures about significant segment expenses. The guidance also expands the interim disclosure requirements. The guidance is to be applied on a retrospective basis to the financial statements and footnotes and early adoption is permitted. Fiscal periods beginning after December 15, 2023 and interim periods beginning after December 31, 2024 The Company is currently evaluating the impact the guidance will have on its disclosures for the year ended December 31, 2024 and interim periods for fiscal year 2025. ASU 2023-09 - Improvements to Income Tax Disclosures In December 2023, the FASB issued guidance on modifying the disclosure requirements to increase transparency about income tax information through improvements to income tax disclosures primarily related to the rate reconciliation and income taxes paid information. The guidance is to be applied on a prospective basis to the financial statements and footnotes, however, retrospective adoption is also permitted. The guidance also permits early adoption. Fiscal periods beginning after December 15, 2024 The Company is currently evaluating the impact the guidance will have on its disclosures for the year ended December 31, 2025.
Net income per share	Basic net income per share is computed by dividing net income by the weighted average number of shares of common stock outstanding during the applicable period. Diluted net income per share is computed by dividing net income by the total of the weighted average number of shares of common stock outstanding during the applicable period, plus the effect of non-vested performance shares and restricted stock units.
Disaggregation of revenue	Revenue is recognized when a performance obligation is satisfied by transferring control over a product or service to a customer. Revenue includes revenue from the sales of construction materials and contracting services. Revenue is measured based on consideration specified in a contract with a customer and excludes any sales incentives and amounts collected on behalf of third parties. Knife River is considered an agent for certain taxes collected from customers. As such, we present revenues net of these taxes at the time of sale to be remitted to governmental authorities, including sales and use taxes. Revenue for construction materials is recognized at a point in time when delivery of the products has taken place. Contracting revenue is recognized over time using an input method based on the cost-to-cost measure of progress on a project.
Fair value measurements	We measure our investments in certain fixed-income and equity securities at fair value with changes in fair value recognized in income.
Business segment data	Company’s reportable segments, Pacific, Northwest, Mountain, Central and Energy Services, which are based on our method of internal reporting and management of our business. Four of the reportable segments are aligned by key geographic areas due to the production of construction materials and related contracting services and one is based on product line. Each segment is led by a segment manager who reports to the Company’s chief operating officer, who is also the Company's chief operating decision maker, along with the chief executive officer. The chief operating decision maker evaluates the performance of the segments and allocates resources to them based on earnings before interest, taxes, depreciation, depletion and amortization ("EBITDA"). In the fourth quarter of 2023, we realigned our reportable segments to better support our operational strategies. The liquid asphalt and related services portion of the Pacific segment's businesses are now reported under the Energy Services segment. In addition, the North Central and South operating regions have been aggregated into one reportable segment, Central. We also reallocated certain amounts to the operating segments that were previously reported within Corporate Services. All periods have been recast to conform with the revised presentation. Each geographic segment offers a vertically integrated suite of products and services, including aggregates, ready-mix concrete, asphalt and contracting services, while the Energy Services segment produces and supplies liquid asphalt, primarily for use in asphalt road construction, and is a supplier to some of the other segments.
Commitments and contingencies	The Company is party to claims and lawsuits arising out of its business and that of its consolidated subsidiaries, which may include, but are not limited to, matters involving property damage, personal injury, and environmental, contractual and statutory obligations. We accrue a liability for those contingencies when the incurrence of a loss is probable and the amount can be reasonably estimated. If a range of amounts can be reasonably estimated and no amount within the range is a better estimate than any other amount, then the minimum of the range is accrued. We do not accrue liabilities when the likelihood that the liability has been incurred is probable but the amount cannot be reasonably estimated or when the liability is believed to be only reasonably possible or remote. For contingencies where an unfavorable outcome is probable or reasonably possible and which are material, we disclose the nature of the contingency and, in some circumstances, an estimate of the possible loss. Accruals are based on the best information available, but in certain situations management is unable to estimate an amount or range of a reasonably possible loss including, but not limited to when: (1) the damages are unsubstantiated or indeterminate, (2) the proceedings are in the early stages, (3) numerous parties are involved, or (4) the matter involves novel or unsettled legal theories.

v3.24.2.u1

Basis of presentation (Tables)	6 Months Ended
	Jun. 30, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Cash and Cash Equivalents	Restricted cash represents deposits held by our captive insurance company that is required by state insurance regulations to remain in the captive insurance company. Cash, cash equivalents and restricted cash on the Consolidated Balance Sheets is comprised of: June 30, 2024 June 30, 2023 December 31, 2023 (In thousands) Cash and cash equivalents $ 15,468 $ 40,089 $ 219,324 Restricted cash 41,701 28,400 42,996 Cash, cash equivalents and restricted cash $ 57,169 $ 68,489 $ 262,320
Restrictions on Cash and Cash Equivalents	Restricted cash represents deposits held by our captive insurance company that is required by state insurance regulations to remain in the captive insurance company. Cash, cash equivalents and restricted cash on the Consolidated Balance Sheets is comprised of: June 30, 2024 June 30, 2023 December 31, 2023 (In thousands) Cash and cash equivalents $ 15,468 $ 40,089 $ 219,324 Restricted cash 41,701 28,400 42,996 Cash, cash equivalents and restricted cash $ 57,169 $ 68,489 $ 262,320

v3.24.2.u1

New accounting standards (Tables)	6 Months Ended
	Jun. 30, 2024
Accounting Policies [Abstract]
Accounting Standards Update and Change in Accounting Principle	The following table provides a brief description of the accounting pronouncements applicable to Knife River and the potential impact on its consolidated financial statements and/or disclosures: Standard Description Standard Effective Date Impact on financial statements/disclosures Recently issued Financial Accounting Standards Board (FASB) accounting standards updates ("ASU") not yet adopted ASU 2023-07 - Improvements to Reportable Segment Disclosures In November 2023, the FASB issued guidance on modifying the disclosure requirements to improve reportable segment disclosure requirements through enhanced disclosures about significant segment expenses. The guidance also expands the interim disclosure requirements. The guidance is to be applied on a retrospective basis to the financial statements and footnotes and early adoption is permitted. Fiscal periods beginning after December 15, 2023 and interim periods beginning after December 31, 2024 The Company is currently evaluating the impact the guidance will have on its disclosures for the year ended December 31, 2024 and interim periods for fiscal year 2025. ASU 2023-09 - Improvements to Income Tax Disclosures In December 2023, the FASB issued guidance on modifying the disclosure requirements to increase transparency about income tax information through improvements to income tax disclosures primarily related to the rate reconciliation and income taxes paid information. The guidance is to be applied on a prospective basis to the financial statements and footnotes, however, retrospective adoption is also permitted. The guidance also permits early adoption. Fiscal periods beginning after December 15, 2024 The Company is currently evaluating the impact the guidance will have on its disclosures for the year ended December 31, 2025.

v3.24.2.u1

Receivables and allowance for expected credit losses (Tables)	6 Months Ended
	Jun. 30, 2024
Credit Loss [Abstract]
Schedule of Accounts, Notes, Loans and Financing Receivable	Receivables were as follows: June 30, 2024 June 30, 2023 December 31, 2023 (In thousands) Trade receivables $ 206,673 $ 220,948 $ 124,134 Contract receivables 188,120 173,318 112,037 Retention receivables 32,649 30,224 36,782 Receivables, gross 427,442 424,490 272,953 Less expected credit loss 4,501 5,870 6,168 Receivables, net $ 422,941 $ 418,620 $ 266,785
Accounts Receivable, Allowance for Credit Loss	Details of the Company's expected credit losses were as follows: Pacific Northwest Mountain Central Energy Services Total   (In thousands) As of December 31, 2023 $ 2,053  $ 1,004  $ 2,293  $ 718  $ 100  $ 6,168  Current expected credit loss provision 177  (223) (47) 87  —  (6) Less write-offs charged against the allowance (53) 133  2  3  —  85  At March 31, 2024 $ 2,283  $ 648  $ 2,244  $ 802  $ 100  $ 6,077  Current expected credit loss provision 25  79  27  151  1  283  Less write-offs charged against the allowance 513  11  1,122  212  1  1,859  At June 30, 2024 $ 1,795  $ 716  $ 1,149  $ 741  $ 100  $ 4,501  Pacific Northwest Mountain Central Energy Services Total   (In thousands) As of December 31, 2022 $ 1,945  $ 1,253  $ 1,278  $ 901  $ 100  $ 5,477  Current expected credit loss provision 45  313  164  (90) —  432  Less write-offs charged against the allowance 1  68  18  —  —  87  At March 31, 2023 $ 1,989  $ 1,498  $ 1,424  $ 811  $ 100  $ 5,822  Current expected credit loss provision 8  74  631  (131) 1  583  Less write-offs charged against the allowance 17  512  3  2  1  535  At June 30, 2023 $ 1,980  $ 1,060  $ 2,052  $ 678  $ 100  $ 5,870

v3.24.2.u1

Inventories (Tables)	6 Months Ended
	Jun. 30, 2024
Inventory Disclosure [Abstract]
Inventories	Inventories on the Consolidated Balance Sheets were as follows:   June 30, 2024 June 30, 2023 December 31, 2023   (In thousands) Finished products $ 245,983  $ 227,683  $ 225,319  Raw materials 100,029  104,689  61,776  Supplies and parts 39,366  42,005  32,528  Total $ 385,378  $ 374,377  $ 319,623

v3.24.2.u1

Net income per share (Tables)	6 Months Ended
	Jun. 30, 2024
Earnings Per Share [Abstract]
Schedule of Weighted Average Number of Shares	Basic and diluted net income per share are calculated as follows, based on a reconciliation of the weighted-average common shares outstanding on a basic and diluted basis: Three Months Ended Six Months Ended June 30, June 30, 2024 2023 2024 2023 (In thousands, except per share amounts) Net income $ 77,929  $ 56,836  $ 30,301  $ 15,516  Weighted average common shares outstanding - basic 56,611  56,566  56,601  56,566  Effect of dilutive performance shares and restricted stock units 200  33  190  17  Weighted average common shares outstanding - diluted 56,811  56,599  56,791  56,583  Shares excluded from the calculation of diluted loss per share 16  —  21  —  Net income per share - basic $ 1.38  $ 1.00  $ .54  $ .27  Net income per share - diluted $ 1.37  $ 1.00  $ .53  $ .27

v3.24.2.u1

Accumulated other comprehensive loss (Tables)	6 Months Ended
	Jun. 30, 2024
Equity [Abstract]
Schedule of Accumulated Other Comprehensive Loss	The after-tax changes in the components of accumulated other comprehensive loss were as follows: Net Unrealized Loss on Derivative  Instruments  Qualifying as Hedges Postretirement  Liability Adjustment Total Accumulated  Other Comprehensive  Loss   (In thousands) As of December 31, 2023 $ —  $ (11,319) $ (11,319) Amounts reclassified from accumulated other comprehensive loss —  78  78  Net current-period other comprehensive income —  78  78  At March 31, 2024 $ —  $ (11,241) $ (11,241) Amounts reclassified from accumulated other comprehensive loss —  77  77  Net current-period other comprehensive income —  77  77  At June 30, 2024 $ —  $ (11,164) $ (11,164) Net Unrealized Loss on Derivative  Instruments  Qualifying as Hedges Postretirement  Liability Adjustment Total Accumulated  Other Comprehensive  Loss   (In thousands) As of December 31, 2022 $ (90) $ (12,262) $ (12,352) Amounts reclassified from accumulated other comprehensive loss 46  47  93  Net current-period other comprehensive income 46  47  93  At March 31, 2023 $ (44) $ (12,215) $ (12,259) Other comprehensive loss before reclassification —  (17) (17) Amounts reclassified from accumulated other comprehensive loss 44  48  92  Net current-period other comprehensive income 44  31  75  At June 30, 2023 $ —  $ (12,184) $ (12,184)
Reclassification out of Accumulated Other Comprehensive Loss	The following amounts were reclassified out of accumulated other comprehensive loss into net income. The amounts presented in parenthesis indicate a decrease to net income on the Consolidated Statements of Operations. The reclassifications were as follows: Three Months Ended Six Months Ended Location on Consolidated Statements of Operations June 30, June 30, 2024 2023 2024 2023 (In thousands) Reclassification adjustment for loss on derivative instruments included in net income $ —  $ (57) $ —  $ (118) Interest expense —  13  —  28  Income taxes —  (44) —  (90) Amortization of postretirement liability losses included in net periodic benefit cost (102) (63) (205) (126) Other income 25  15  50  31  Income taxes (77) (48) (155) (95) Total reclassifications $ (77) $ (92) $ (155) $ (185)

v3.24.2.u1

Revenue from contracts with customers (Tables)	6 Months Ended
	Jun. 30, 2024
Revenue from Contract with Customer [Abstract]
Schedule of Disaggregation of Revenue	Three Months Ended June 30, 2024 Pacific Northwest Mountain Central Energy Services Corporate Services and Eliminations Total (In thousands) Aggregates $ 31,259  $ 53,061  $ 31,138  $ 42,943  $ —  $ —  $ 158,401  Ready-mix concrete 36,667  45,660  34,967  62,225  —  —  179,519  Asphalt 8,622  32,529  32,860  45,268  —  —  119,279  Liquid asphalt —  —  —  —  65,304  —  65,304  Other 42,357  5,574  7  10,875  14,386  4,511  77,710  Contracting services public-sector 20,713  71,299  90,023  102,820  —  —  284,855  Contracting services private-sector 14,222  25,596  41,552  5,549  —  —  86,919  Internal sales (22,013) (33,494) (36,778) (55,077) (13,447) (4,272) (165,081) Revenues from contracts with customers $ 131,827  $ 200,225  $ 193,769  $ 214,603  $ 66,243  $ 239  $ 806,906  Three Months Ended June 30, 2023 Pacific Northwest Mountain Central Energy Services Corporate Services and Eliminations Total (In thousands) Aggregates $ 27,446  $ 47,966  $ 28,866  $ 42,138  $ —  $ —  $ 146,416  Ready-mix concrete 40,526  44,583  34,506  65,283  —  —  184,898  Asphalt 6,275  34,518  29,472  54,672  —  —  124,937  Liquid asphalt —  —  —  —  72,920  —  72,920  Other 39,802  4,335  8  10,909  13,849  1,341  70,244  Contracting services public-sector 16,848  53,301  80,381  114,025  —  —  264,555  Contracting services private-sector 16,575  29,353  37,317  5,637  —  —  88,882  Internal sales (22,393) (35,322) (34,796) (61,630) (13,706) 184  (167,663) Revenues from contracts with customers $ 125,079  $ 178,734  $ 175,754  $ 231,034  $ 73,063  $ 1,525  $ 785,189  Six Months Ended June 30, 2024 Pacific Northwest Mountain Central Energy Services Corporate Services and Eliminations Total (In thousands) Aggregates $ 50,809  $ 92,459  $ 40,592  $ 58,814  $ —  $ —  $ 242,674  Ready-mix concrete 67,887  77,436  48,803  85,248  —  —  279,374  Asphalt 10,969  40,766  33,690  50,326  —  —  135,751  Liquid asphalt —  —  —  —  76,340  —  76,340  Other 67,686  9,147  13  12,773  17,448  9,654  116,721  Contracting services public-sector 26,188  107,343  115,882  123,853  —  —  373,266  Contracting services private-sector 22,296  40,628  55,355  5,724  —  —  124,003  Internal sales (35,621) (48,402) (40,740) (61,173) (16,428) (9,269) (211,633) Revenues from contracts with customers $ 210,214  $ 319,377  $ 253,595  $ 275,565  $ 77,360  $ 385  $ 1,136,496  Six Months Ended June 30, 2023 Pacific Northwest Mountain Central Energy Services Corporate Services and Eliminations Total (In thousands) Aggregates $ 46,143  $ 90,540  $ 38,532  $ 54,722  $ —  $ —  $ 229,937  Ready-mix concrete 66,670  78,488  48,876  87,633  —  —  281,667  Asphalt 7,591  41,445  30,282  59,238  —  —  138,556  Liquid asphalt —  —  —  —  81,206  —  81,206  Other 63,222  7,016  11  12,495  16,040  1,767  100,551  Contracting services public-sector 20,819  70,304  108,619  136,885  —  —  336,627  Contracting services private-sector 19,474  55,115  50,762  6,442  —  —  131,793  Internal sales (33,197) (48,254) (40,710) (68,761) (15,928) (398) (207,248) Revenues from contracts with customers $ 190,722  $ 294,654  $ 236,372  $ 288,654  $ 81,318  $ 1,369  $ 1,093,089

v3.24.2.u1

Uncompleted contracts (Tables)	6 Months Ended
	Jun. 30, 2024
Revenue from Contract with Customer [Abstract]
Contract with Customer, Contract Asset, Contract Liability, and Receivable	The changes in contract assets and liabilities were as follows: June 30, 2024 December 31, 2023 Change Location on Consolidated Balance Sheets (In thousands) Contract assets $ 49,150  $ 27,293  $ 21,857  Costs and estimated earnings in excess of billings on uncompleted contracts Contract liabilities (45,123) (51,376) 6,253  Billings in excess of costs and estimated earnings on uncompleted contracts Net contract assets (liabilities) $ 4,027  $ (24,083) $ 28,110  June 30, 2023 December 31, 2022 Change Location on Consolidated Balance Sheets (In thousands) Contract assets $ 58,020  $ 31,145  $ 26,875  Costs and estimated earnings in excess of billings on uncompleted contracts Contract liabilities (44,590) (39,843) (4,747) Billings in excess of costs and estimated earnings on uncompleted contracts Net contract assets (liabilities) $ 13,430  $ (8,698) $ 22,128

v3.24.2.u1

Goodwill and other intangible assets (Tables)	6 Months Ended
	Jun. 30, 2024
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill	The changes in the carrying amount of goodwill were as follows: Balance at January 1, 2024 Goodwill Acquired During the Year Measurement Period Adjustments Reallocation of Goodwill Balance at June 30, 2024   (In thousands) Pacific $ 32,621  $ —  $ —  $ —  $ 32,621  Northwest 90,978  —  —  —  90,978  Mountain 26,816  —  —  —  26,816  North Central 75,879  735  —  —  76,614  South 38,708  —  —  —  38,708  Energy Services 9,476  —  —  —  9,476  Total $ 274,478  $ 735  $ —  $ —  $ 275,213  Balance at January 1, 2023 Goodwill Acquired During the Year Measurement Period Adjustments Reallocation of Goodwill Balance at June 30, 2023   (In thousands) Pacific $ 38,339  $ —  $ (62) $ —  $ 38,277  Northwest 90,978  —  —  —  90,978  Mountain 26,816  —  —  —  26,816  North Central 75,879  —  —  —  75,879  South 38,708  —  —  —  38,708  Energy Services 3,820  —  —  —  3,820  Total $ 274,540  $ —  $ (62) $ —  $ 274,478  Balance at January 1, 2023 Goodwill Acquired During the Year Measurement Period Adjustments Reallocation of Goodwill Balance at December 31, 2023   (In thousands) Pacific $ 38,339  $ —  $ (62) $ (5,656) $ 32,621  Northwest 90,978  —  —  —  90,978  Mountain 26,816  —  —  —  26,816  North Central 75,879  —  —  —  75,879  South 38,708  —  —  —  38,708  Energy Services 3,820  —  —  5,656  9,476  Total $ 274,540  $ —  $ (62) $ —  $ 274,478
Schedule of Finite-Lived Intangible Assets	Other amortizable intangible assets were as follows:   June 30, 2024 June 30, 2023 December 31, 2023   (In thousands) Customer relationships $ 18,868  $ 18,540  $ 18,540  Less accumulated amortization 9,977  8,235  9,102    8,891  10,305  9,438  Noncompete agreements 3,784  4,039  4,039  Less accumulated amortization 3,283  3,239  3,473  501  800  566  Other 1,796  2,479  2,479  Less accumulated amortization 1,044  1,474  1,662    752  1,005  817  Total $ 10,144  $ 12,110  $ 10,821
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense	Estimated amortization expense for identifiable intangible assets as of June 30, 2024, was: Remainder of 2024 2025 2026 2027 2028 Thereafter (In thousands) Amortization expense $ 1,192  $ 1,964  $ 1,784  $ 1,761  $ 1,717  $ 1,726

v3.24.2.u1

Fair value measurements (Tables)	6 Months Ended
	Jun. 30, 2024
Fair Value Disclosures [Abstract]
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis	The Company's assets measured at fair value on a recurring basis were as follows:   Fair Value Measurements at June 30, 2024, Using     Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Balance at June 30, 2024 (In thousands) Assets:         Money market funds $ —  $ 3,982  $ —  $ 3,982  Insurance contracts* —  27,289  —  27,289  Total assets measured at fair value $ —  $ 31,271  $ —  $ 31,271  *    The insurance contracts invest approximately 36 percent in fixed-income investments, 23 percent in common stock of large-cap companies, 15 percent in cash equivalents, 9 percent in common stock of mid-cap companies, 9 percent target date investments, 5 percent in common stock of small-cap companies, 1 percent in international investments, 1 percent in real estate investments and 1 percent in high yield investments.   Fair Value Measurements at June 30, 2023, Using     Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Balance at June 30, 2023 (In thousands) Assets:         Money market funds $ —  $ 7,529  $ —  $ 7,529  Insurance contracts* —  19,141  —  19,141  Total assets measured at fair value $ —  $ 26,670  $ —  $ 26,670  *    The insurance contracts invest approximately 47 percent in fixed-income investments, 20 percent in cash equivalents, 15 percent in common stock of large-cap companies, 8 percent in common stock of mid-cap companies, 6 percent in common stock of small-cap companies and 4 percent target date investments.   Fair Value Measurements at December 31, 2023, Using   Quoted Prices in Active Markets for Identical Assets  (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs  (Level 3) Balance at December 31, 2023 (In thousands) Assets:         Money market funds $ —  $ 3,241  $ —  $ 3,241  Insurance contracts* —  24,896  —  24,896  Total assets measured at fair value $ —  $ 28,137  $ —  $ 28,137  *    The insurance contracts invest approximately 40 percent in fixed-income investments, 19 percent in common stock of large-cap companies, 18 percent in cash equivalents, 8 percent in target date investments, 8 percent in common stock of mid-cap companies, 6 percent in common stock of small-cap companies and 1 percent in international investments.
Fair Value, by Balance Sheet Grouping	The estimated fair value of the Company's Level 2 long-term debt was as follows:   June 30, 2024 June 30, 2023 December 31, 2023   (In thousands) Carrying amount $ 693,483  $ 855,000  $ 696,985  Fair value $ 712,852  $ 862,420  $ 725,086

v3.24.2.u1

Debt (Tables)	6 Months Ended
	Jun. 30, 2024
Debt Disclosure [Abstract]
Schedule of Long-Term Debt Instruments	Long-term debt outstanding was as follows:   Weighted Average Interest Rate at June 30, 2024 June 30, 2024 June 30, 2023 December 31, 2023   (In thousands) Term loan agreement due on May 31, 2028 7.20  % $ 268,125  $ 275,000  $ 271,562  Revolving credit agreement —  % —  155,000  —  Senior notes due on May 1, 2031 7.75  % 425,000  425,000  425,000  Other notes due on January 1, 2061 —  % 358  511  423  Less unamortized debt issuance costs 13,945  16,382  15,326  Total long-term debt 679,538  839,129  681,659  Less current maturities 7,072  7,082  7,082  Net long-term debt $ 672,466  $ 832,047  $ 674,577
Schedule of Maturities of Long-Term Debt	Long-term debt maturities, which excludes unamortized debt issuance costs, at June 30, 2024, were as follows: Remainder of 2024 2025 2026 2027 2028 Thereafter (In thousands) Long-term debt maturities $ 3,634  $ 10,473  $ 13,750  $ 17,188  $ 223,438  $ 425,000

v3.24.2.u1

Cash flow information (Tables)	6 Months Ended
	Jun. 30, 2024
Supplemental Cash Flow Information [Abstract]
Schedule of Cash Flow, Supplemental Disclosures	Cash expenditures for interest and income taxes were as follows: Six Months Ended   June 30,   2024 2023    (In thousands) Interest paid, net $ 27,993  $ 24,802  Income taxes paid, net $ 1,662  $ 558  Noncash investing and financing transactions were as follows: Six Months Ended June 30, 2024 2023  (In thousands) Right-of-use assets obtained in exchange for new operating lease liabilities $ 10,844  $ 7,552  Property, plant and equipment additions in accounts payable $ 5,098  $ 3,359  Equity contribution from Centennial related to the Separation $ —  $ 64,724  Equity contribution to MDU Resources for asset/liability transfers related to the Separation $ —  $ (1,548) MDU Resources' stock issued prior to spin in connection with a business combination $ —  $ 383

v3.24.2.u1

Business segment data (Tables)	6 Months Ended
	Jun. 30, 2024
Segment Reporting [Abstract]
Schedule of Segment Reporting Information, by Segment	The information below follows the same accounting policies as described in the audited financial statements and notes included in the Company's 2023 Annual Report. Information on the Company's segments was as follows: Three Months Ended Six Months Ended June 30, June 30,   2024  2023  2024  2023    (In thousands) External operating revenues:       Pacific $ 131,827  $ 125,079  $ 210,214  $ 190,722  Northwest 200,225  178,734  319,377  294,654  Mountain 193,769  175,754  253,595  236,372  Central 214,603  231,034  275,565  288,654  Energy Services 66,243  73,063  77,360  81,318  Total reportable segment external operating revenues $ 806,667  $ 783,664  $ 1,136,111  $ 1,091,720  Intersegment operating revenues: Pacific $ 22,013  $ 22,393  $ 35,621  $ 33,197  Northwest 33,494  35,322  48,402  48,254  Mountain 36,778  34,796  40,740  40,710  Central 55,077  61,630  61,173  68,761  Energy Services 13,447  13,706  16,428  15,928  Total reportable segment intersegment operating revenues $ 160,809  $ 167,847  $ 202,364  $ 206,850  EBITDA:         Pacific $ 17,789  $ 17,457  $ 17,046  $ 17,605  Northwest 50,762  38,871  70,916  52,868  Mountain 43,119  30,323  37,054  26,570  Central 36,188  28,399  17,466  11,500  Energy Services 19,367  21,781  16,884  18,804  Total reportable segment EBITDA $ 167,225  $ 136,831  $ 159,366  $ 127,347
Reconciliation of Revenue from Segments to Consolidated	A reconciliation of consolidated operating revenues to reportable segment operating revenues is as follows: Three Months Ended Six Months Ended June 30, June 30, 2024 2023 2024 2023 (In thousands) Consolidated operating revenues $ 806,906  $ 785,189  $ 1,136,496  $ 1,093,089  Plus: Intersegment operating revenues 165,081  167,663  211,633  207,248  Less: Corporate Services revenue 4,511  1,341  9,654  1,767  Total reportable segment operating revenues $ 967,476  $ 951,511  $ 1,338,475  $ 1,298,570
Segment, Reconciliation of Other Items from Segments to Consolidated	A reconciliation of consolidated net income before income taxes to reportable segment EBITDA is as follows: Three Months Ended Six Months Ended June 30, June 30, 2024 2023 2024 2023 (In thousands) Total consolidated net income before income taxes $ 104,114  $ 76,855  $ 40,160  $ 23,623  Plus: Depreciation, depletion and amortization 34,512  31,130  66,724  60,760  Interest expense, net* 12,809  17,130  23,955  26,625  Less: Corporate Services EBITDA (15,790) (11,716) (28,527) (16,339) Total EBITDA for reportable segments $ 167,225  $ 136,831  $ 159,366  $ 127,347  *Interest, net is interest expense net of interest income.

v3.24.2.u1

Background (Details)	1 Months Ended	6 Months Ended
	Nov. 30, 2023 shares	Jun. 30, 2024 reportableSegment state $ / shares	Dec. 31, 2023 $ / shares	Jun. 30, 2023 $ / shares	May 31, 2023 $ / shares
Organization [Line Items]
Number of states in which entity operates | state		14
Number of reportable segments | reportableSegment		5
Separation transaction, percent of outstanding shares distributed					90.00%
Common stock, par value (in dollars per share) | $ / shares		$ 0.01	$ 0.01	$ 0.01	$ 0.01
Separation transaction, outstanding shares distributed (in shares) | shares	5,656,621
Separation transaction, distribution ratio					0.25
Knife River
Organization [Line Items]
Subsidiary, ownership percentage, noncontrolling owner					10.00%

v3.24.2.u1

Basis of presentation - Narrative (Details) - Related Party - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2023
Selling, General and Administrative Expenses
Accounting Policies [Line Items]
Costs and expenses, related party	$ 4,700	$ 9,600
Other Nonoperating Income (Expense)
Accounting Policies [Line Items]
Costs and expenses, related party	$ 300	$ 600

v3.24.2.u1

Basis of presentation - Schedule of Cash and Cash Equivalents (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023	Jun. 30, 2023	Dec. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Cash and cash equivalents	$ 15,468	$ 219,324	$ 40,089
Restricted cash	41,701	42,996	28,400
Cash, cash equivalents and restricted cash	$ 57,169	$ 262,320	$ 68,489	$ 10,090

v3.24.2.u1

Receivables and allowance for expected credit losses - Narrative (Details) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023	Jun. 30, 2023
Credit Loss [Abstract]
Accounts receivable, noncurrent, 90 days or more past due, still accruing	$ 7.4	$ 16.7	$ 11.6

v3.24.2.u1

Receivables and allowance for expected credit losses - Summary of Receivables (Details) - Trade Accounts Receivable - USD ($) $ in Thousands	Jun. 30, 2024	Mar. 31, 2024	Dec. 31, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022
Accounts, Notes, Loans and Financing Receivable [Line Items]
Trade receivables	$ 206,673		$ 124,134	$ 220,948
Contract receivables	188,120		112,037	173,318
Retention receivables	32,649		36,782	30,224
Receivables, gross	427,442		272,953	424,490
Less expected credit loss	4,501	$ 6,077	6,168	5,870	$ 5,822	$ 5,477
Receivables, net	$ 422,941		$ 266,785	$ 418,620

v3.24.2.u1

Receivables and allowance for expected credit losses - Details of Expected Credit Losses (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2024	Jun. 30, 2023
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Current expected credit loss provision					$ 277	$ 1,015
Trade Accounts Receivable
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 6,077	$ 6,168	$ 5,822	$ 5,477	6,168	5,477
Current expected credit loss provision	283	(6)	583	432
Less write-offs charged against the allowance	1,859	85	535	87
Ending balance	4,501	6,077	5,870	5,822	4,501	5,870
Pacific | Trade Accounts Receivable
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	2,283	2,053	1,989	1,945	2,053	1,945
Current expected credit loss provision	25	177	8	45
Less write-offs charged against the allowance	513	(53)	17	1
Ending balance	1,795	2,283	1,980	1,989	1,795	1,980
Northwest | Trade Accounts Receivable
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	648	1,004	1,498	1,253	1,004	1,253
Current expected credit loss provision	79	(223)	74	313
Less write-offs charged against the allowance	11	133	512	68
Ending balance	716	648	1,060	1,498	716	1,060
Mountain | Trade Accounts Receivable
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	2,244	2,293	1,424	1,278	2,293	1,278
Current expected credit loss provision	27	(47)	631	164
Less write-offs charged against the allowance	1,122	2	3	18
Ending balance	1,149	2,244	2,052	1,424	1,149	2,052
Central | Trade Accounts Receivable
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	802	718	811	901	718	901
Current expected credit loss provision	151	87	(131)	(90)
Less write-offs charged against the allowance	212	3	2	0
Ending balance	741	802	678	811	741	678
Energy Services | Trade Accounts Receivable
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	100	100	100	100	100	100
Current expected credit loss provision	1	0	1	0
Less write-offs charged against the allowance	1	0	1	0
Ending balance	$ 100	$ 100	$ 100	$ 100	$ 100	$ 100

v3.24.2.u1

Inventories (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023	Jun. 30, 2023
Inventory Disclosure [Abstract]
Finished products	$ 245,983	$ 225,319	$ 227,683
Raw materials	100,029	61,776	104,689
Supplies and parts	39,366	32,528	42,005
Total	$ 385,378	$ 319,623	$ 374,377

v3.24.2.u1

Net income per share- Narrative (Details) - shares	Jun. 30, 2024	Dec. 31, 2023	Jun. 30, 2023
Earnings Per Share [Abstract]
Common stock, issued (in shares)	57,043,841	57,009,542	56,997,350
Treasury stock held at cost (in shares)	431,136	431,136	431,136

v3.24.2.u1

Net income per share- Reconciliation of the Weighted-Average Common Shares Outstanding on a Basic and Diluted Basis (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2024	Jun. 30, 2023
Earnings Per Share [Abstract]
Net income (loss)	$ 77,929	$ (47,629)	$ 56,836	$ (41,320)	$ 30,301	$ 15,516
Weighted average common shares outstanding - basic (in shares)	56,611		56,566		56,601	56,566
Effect of dilutive performance shares and restricted stock units (in shares)	200		33		190	17
Weighted average common shares outstanding - diluted (in shares)	56,811		56,599		56,791	56,583
Shares excluded from the calculation of diluted loss per share (in shares)	16		0		21	0
Net income per share - basic (in dollars per share)	$ 1.38		$ 1.00		$ 0.54	$ 0.27
Net income per share - diluted (in dollars per share)	$ 1.37		$ 1.00		$ 0.53	$ 0.27

v3.24.2.u1

Accumulated other comprehensive loss - After-Tax Changes in the Components of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2023	Mar. 31, 2023
Accumulated other comprehensive loss [Roll Forward]
Beginning balance	$ 1,218,627	$ 1,266,012	$ 974,769	$ 1,028,589
Ending balance	1,298,706	1,218,627	1,094,852	974,769
Net Unrealized Loss on Derivative Instruments Qualifying as Hedges
Accumulated other comprehensive loss [Roll Forward]
Beginning balance	0	0	(44)	(90)
Amounts reclassified from accumulated other comprehensive loss	0	0	44	46
Net current-period other comprehensive income	0	0	44	46
Other comprehensive loss before reclassification			0
Ending balance	0	0	0	(44)
Postretirement Liability Adjustment
Accumulated other comprehensive loss [Roll Forward]
Beginning balance	(11,241)	(11,319)	(12,215)	(12,262)
Amounts reclassified from accumulated other comprehensive loss	77	78	48	47
Net current-period other comprehensive income	77	78	31	47
Other comprehensive loss before reclassification			(17)
Ending balance	(11,164)	(11,241)	(12,184)	(12,215)
Total Accumulated Other Comprehensive Loss
Accumulated other comprehensive loss [Roll Forward]
Beginning balance	(11,241)	(11,319)	(12,259)	(12,352)
Amounts reclassified from accumulated other comprehensive loss	77	78	92	93
Net current-period other comprehensive income	77	78	75	93
Other comprehensive loss before reclassification			(17)
Ending balance	$ (11,164)	$ (11,241)	$ (12,184)	$ (12,259)

v3.24.2.u1

Accumulated other comprehensive loss - Reclassification out of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2024	Jun. 30, 2023
Reclassification adjustment out of accumulated other comprehensive loss [Line Items]
Interest expense	$ (13,936)		$ (19,156)		$ (27,912)	$ (28,651)
Income taxes	(26,185)		(20,019)		(9,859)	(8,107)
Other income	1,304		2,478		5,054	3,304
Net income (loss)	77,929	$ (47,629)	56,836	$ (41,320)	30,301	15,516
Reclassification out of accumulated other comprehensive loss
Reclassification adjustment out of accumulated other comprehensive loss [Line Items]
Net income (loss)	(77)		(92)		(155)	(185)
Net Unrealized Loss on Derivative Instruments Qualifying as Hedges | Reclassification out of accumulated other comprehensive loss | Interest rate contract
Reclassification adjustment out of accumulated other comprehensive loss [Line Items]
Interest expense	0		(57)		0	(118)
Income taxes	0		13		0	28
Net income (loss)	0		(44)		0	(90)
Amortization of postretirement liability losses included in net periodic benefit cost | Reclassification out of accumulated other comprehensive loss
Reclassification adjustment out of accumulated other comprehensive loss [Line Items]
Income taxes	25		15		50	31
Other income	(102)		(63)		(205)	(126)
Net income (loss)	$ (77)		$ (48)		$ (155)	$ (95)

v3.24.2.u1

Revenue from contracts with customers (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Disaggregation of Revenue [Line Items]
Revenues	$ 806,906	$ 785,189	$ 1,136,496	$ 1,093,089
Operating Segments
Disaggregation of Revenue [Line Items]
Revenues	806,667	783,664	1,136,111	1,091,720
Intersegment eliminations
Disaggregation of Revenue [Line Items]
Revenues	(165,081)	(167,663)	(211,633)	(207,248)
Aggregates
Disaggregation of Revenue [Line Items]
Revenues	158,401	146,416	242,674	229,937
Ready-mix concrete
Disaggregation of Revenue [Line Items]
Revenues	179,519	184,898	279,374	281,667
Asphalt
Disaggregation of Revenue [Line Items]
Revenues	119,279	124,937	135,751	138,556
Liquid Asphalt
Disaggregation of Revenue [Line Items]
Revenues	65,304	72,920	76,340	81,206
Other
Disaggregation of Revenue [Line Items]
Revenues	77,710	70,244	116,721	100,551
Contracting services public-sector
Disaggregation of Revenue [Line Items]
Revenues	284,855	264,555	373,266	336,627
Contracting services private-sector
Disaggregation of Revenue [Line Items]
Revenues	86,919	88,882	124,003	131,793
Pacific | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues	131,827	125,079	210,214	190,722
Pacific | Intersegment eliminations
Disaggregation of Revenue [Line Items]
Revenues	(22,013)	(22,393)	(35,621)	(33,197)
Pacific | Aggregates
Disaggregation of Revenue [Line Items]
Revenues	31,259	27,446	50,809	46,143
Pacific | Ready-mix concrete
Disaggregation of Revenue [Line Items]
Revenues	36,667	40,526	67,887	66,670
Pacific | Asphalt
Disaggregation of Revenue [Line Items]
Revenues	8,622	6,275	10,969	7,591
Pacific | Liquid Asphalt
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Pacific | Other
Disaggregation of Revenue [Line Items]
Revenues	42,357	39,802	67,686	63,222
Pacific | Contracting services public-sector
Disaggregation of Revenue [Line Items]
Revenues	20,713	16,848	26,188	20,819
Pacific | Contracting services private-sector
Disaggregation of Revenue [Line Items]
Revenues	14,222	16,575	22,296	19,474
Northwest | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues	200,225	178,734	319,377	294,654
Northwest | Intersegment eliminations
Disaggregation of Revenue [Line Items]
Revenues	(33,494)	(35,322)	(48,402)	(48,254)
Northwest | Aggregates
Disaggregation of Revenue [Line Items]
Revenues	53,061	47,966	92,459	90,540
Northwest | Ready-mix concrete
Disaggregation of Revenue [Line Items]
Revenues	45,660	44,583	77,436	78,488
Northwest | Asphalt
Disaggregation of Revenue [Line Items]
Revenues	32,529	34,518	40,766	41,445
Northwest | Liquid Asphalt
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Northwest | Other
Disaggregation of Revenue [Line Items]
Revenues	5,574	4,335	9,147	7,016
Northwest | Contracting services public-sector
Disaggregation of Revenue [Line Items]
Revenues	71,299	53,301	107,343	70,304
Northwest | Contracting services private-sector
Disaggregation of Revenue [Line Items]
Revenues	25,596	29,353	40,628	55,115
Mountain | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues	193,769	175,754	253,595	236,372
Mountain | Intersegment eliminations
Disaggregation of Revenue [Line Items]
Revenues	(36,778)	(34,796)	(40,740)	(40,710)
Mountain | Aggregates
Disaggregation of Revenue [Line Items]
Revenues	31,138	28,866	40,592	38,532
Mountain | Ready-mix concrete
Disaggregation of Revenue [Line Items]
Revenues	34,967	34,506	48,803	48,876
Mountain | Asphalt
Disaggregation of Revenue [Line Items]
Revenues	32,860	29,472	33,690	30,282
Mountain | Liquid Asphalt
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Mountain | Other
Disaggregation of Revenue [Line Items]
Revenues	7	8	13	11
Mountain | Contracting services public-sector
Disaggregation of Revenue [Line Items]
Revenues	90,023	80,381	115,882	108,619
Mountain | Contracting services private-sector
Disaggregation of Revenue [Line Items]
Revenues	41,552	37,317	55,355	50,762
Central | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues	214,603	231,034	275,565	288,654
Central | Intersegment eliminations
Disaggregation of Revenue [Line Items]
Revenues	(55,077)	(61,630)	(61,173)	(68,761)
Central | Aggregates
Disaggregation of Revenue [Line Items]
Revenues	42,943	42,138	58,814	54,722
Central | Ready-mix concrete
Disaggregation of Revenue [Line Items]
Revenues	62,225	65,283	85,248	87,633
Central | Asphalt
Disaggregation of Revenue [Line Items]
Revenues	45,268	54,672	50,326	59,238
Central | Liquid Asphalt
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Central | Other
Disaggregation of Revenue [Line Items]
Revenues	10,875	10,909	12,773	12,495
Central | Contracting services public-sector
Disaggregation of Revenue [Line Items]
Revenues	102,820	114,025	123,853	136,885
Central | Contracting services private-sector
Disaggregation of Revenue [Line Items]
Revenues	5,549	5,637	5,724	6,442
Energy Services | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues	66,243	73,063	77,360	81,318
Energy Services | Intersegment eliminations
Disaggregation of Revenue [Line Items]
Revenues	(13,447)	(13,706)	(16,428)	(15,928)
Energy Services | Aggregates
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Energy Services | Ready-mix concrete
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Energy Services | Asphalt
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Energy Services | Liquid Asphalt
Disaggregation of Revenue [Line Items]
Revenues	65,304	72,920	76,340	81,206
Energy Services | Other
Disaggregation of Revenue [Line Items]
Revenues	14,386	13,849	17,448	16,040
Energy Services | Contracting services public-sector
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Energy Services | Contracting services private-sector
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Corporate Services and Eliminations | Corporate, Non-Segment & Intersegment Eliminations
Disaggregation of Revenue [Line Items]
Revenues	239	1,525	385	1,369
Corporate Services and Eliminations | Intersegment eliminations
Disaggregation of Revenue [Line Items]
Revenues	(4,272)	184	(9,269)	(398)
Corporate Services and Eliminations | Aggregates
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Corporate Services and Eliminations | Ready-mix concrete
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Corporate Services and Eliminations | Asphalt
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Corporate Services and Eliminations | Liquid Asphalt
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Corporate Services and Eliminations | Other
Disaggregation of Revenue [Line Items]
Revenues	4,511	1,341	9,654	1,767
Corporate Services and Eliminations | Contracting services public-sector
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Corporate Services and Eliminations | Contracting services private-sector
Disaggregation of Revenue [Line Items]
Revenues	$ 0	$ 0	$ 0	$ 0

v3.24.2.u1

Uncompleted contracts - Changes in Contract Assets and Liabilities (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023	Dec. 31, 2022
Revenue from Contract with Customer [Abstract]
Contract assets	$ 49,150	$ 58,020	$ 27,293	$ 31,145
Change in contract assets	21,857	26,875
Billings in excess of costs and estimated earnings on uncompleted contracts	(45,123)	(44,590)	(51,376)	(39,843)
Change in contract liabilities	6,253	(4,747)
Net contract assets (liabilities)	4,027	13,430	$ (24,083)	$ (8,698)
Change in net contract assets (liabilities)	$ 28,110	$ 22,128

v3.24.2.u1

Uncompleted contracts - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Amounts included in contract liability at the beginning of the period	$ 14.4	$ 11.4	$ 44.9	$ 31.7
Contract with customer, performance obligation satisfied in previous period	15.1	$ 7.4	21.2	$ 8.1
Remaining performance obligations	988.5		988.5
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-07-01 | Revenue, Description Of Timing, 13 To 24 Months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligations	44.0		44.0
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-07-01 | Revenue, Description Of Timing, 25 Months Or More
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligations	$ 7.8		$ 7.8
Remaining performance obligations, expected timing	25 months		25 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-07-01 | Revenue, Description Of Timing, 12 Months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligations	$ 936.7		$ 936.7
Remaining performance obligations, expected timing	12 months		12 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-07-01 | Minimum | Revenue, Description Of Timing, 13 To 24 Months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligations, expected timing	13 months		13 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-07-01 | Maximum | Revenue, Description Of Timing, 13 To 24 Months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligations, expected timing	24 months		24 months

v3.24.2.u1

Goodwill and other intangible assets - Goodwill Rollforward (Details) - USD ($) $ in Thousands	6 Months Ended		12 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Goodwill [Roll Forward]
Goodwill, beginning balance	$ 274,478	$ 274,540	$ 274,540
Goodwill Acquired During the Year	735	0	0
Measurement Period Adjustments	0	(62)	(62)
Reallocation of Goodwill	0	0	0
Goodwill, ending balance	275,213	274,478	274,478
Pacific
Goodwill [Roll Forward]
Goodwill, beginning balance	32,621	38,339	38,339
Goodwill Acquired During the Year	0	0	0
Measurement Period Adjustments	0	(62)	(62)
Reallocation of Goodwill	0	0	(5,656)
Goodwill, ending balance	32,621	38,277	32,621
Northwest
Goodwill [Roll Forward]
Goodwill, beginning balance	90,978	90,978	90,978
Goodwill Acquired During the Year	0	0	0
Measurement Period Adjustments	0	0	0
Reallocation of Goodwill	0	0	0
Goodwill, ending balance	90,978	90,978	90,978
Mountain
Goodwill [Roll Forward]
Goodwill, beginning balance	26,816	26,816	26,816
Goodwill Acquired During the Year	0	0	0
Measurement Period Adjustments	0	0	0
Reallocation of Goodwill	0	0	0
Goodwill, ending balance	26,816	26,816	26,816
North Central
Goodwill [Roll Forward]
Goodwill, beginning balance	75,879	75,879	75,879
Goodwill Acquired During the Year	735	0	0
Measurement Period Adjustments	0	0	0
Reallocation of Goodwill	0	0	0
Goodwill, ending balance	76,614	75,879	75,879
South
Goodwill [Roll Forward]
Goodwill, beginning balance	38,708	38,708	38,708
Goodwill Acquired During the Year	0	0	0
Measurement Period Adjustments	0	0	0
Reallocation of Goodwill	0	0	0
Goodwill, ending balance	38,708	38,708	38,708
Energy Services
Goodwill [Roll Forward]
Goodwill, beginning balance	9,476	3,820	3,820
Goodwill Acquired During the Year	0	0	0
Measurement Period Adjustments	0	0	0
Reallocation of Goodwill	0	0	5,656
Goodwill, ending balance	$ 9,476	$ 3,820	$ 9,476

v3.24.2.u1

Goodwill and other intangible assets - Other Amortizable Intangible Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023	Jun. 30, 2023
Finite-Lived Intangible Assets [Line Items]
Total	$ 10,144	$ 10,821	$ 12,110
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	18,868	18,540	18,540
Less accumulated amortization	9,977	9,102	8,235
Total	8,891	9,438	10,305
Noncompete agreements
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	3,784	4,039	4,039
Less accumulated amortization	3,283	3,473	3,239
Total	501	566	800
Other
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	1,796	2,479	2,479
Less accumulated amortization	1,044	1,662	1,474
Total	$ 752	$ 817	$ 1,005

v3.24.2.u1

Goodwill and other intangible assets - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization of intangible assets	$ 526	$ 653	$ 1,100	$ 1,300

v3.24.2.u1

Goodwill and other intangible assets - Schedule of Future Amortization Expense (Details) $ in Thousands	Jun. 30, 2024 USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
Remainder of 2024	$ 1,192
2025	1,964
2026	1,784
2027	1,761
2028	1,717
Thereafter	$ 1,726

v3.24.2.u1

Fair value measurements - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Fair Value Disclosures [Abstract]
Investments used to satisfy nonqualified benefit plans obligations	$ 27,300	$ 19,100	$ 27,300	$ 19,100	$ 24,900
Net unrealized gain (loss) on investments used to satisfy obligations under nonqualified benefit plans	$ 392	$ 197	$ 1,600	$ 1,100

v3.24.2.u1

Fair value measurements - Assets Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023	Jun. 30, 2023
Concentration risks, percentage [Abstract]
Percentage in fixed-income and other investments	36.00%	40.00%	47.00%
Percentage investment in cash and cash equivalents	15.00%	18.00%	20.00%
Percentage investment in common stock of large-cap companies	23.00%	19.00%	15.00%
Percentage investment in common stock of mid-cap companies	9.00%	8.00%	8.00%
Percentage investment in target date investments	9.00%	8.00%	4.00%
Percentage investment in real estate investments	1.00%
Percentage investment in high yield investments	1.00%
Percentage investment in common stock of small-cap companies	5.00%	6.00%	6.00%
Percentage investment in international investments	1.00%	1.00%
Fair value, measurements, recurring
Fair value measurements [Line Items]
Money market funds	$ 3,982	$ 3,241	$ 7,529
Insurance contracts	27,289	24,896	19,141
Total assets measured at fair value	31,271	28,137	26,670
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair value, measurements, recurring
Fair value measurements [Line Items]
Money market funds	0	0	0
Insurance contracts	0	0	0
Total assets measured at fair value	0	0	0
Significant Other Observable Inputs (Level 2) | Fair value, measurements, recurring
Fair value measurements [Line Items]
Money market funds	3,982	3,241	7,529
Insurance contracts	27,289	24,896	19,141
Total assets measured at fair value	31,271	28,137	26,670
Significant Unobservable Inputs (Level 3) | Fair value, measurements, recurring
Fair value measurements [Line Items]
Money market funds	0	0	0
Insurance contracts	0	0	0
Total assets measured at fair value	$ 0	$ 0	$ 0

v3.24.2.u1

Fair value measurements - Fair Value of Long-Term Debt (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023	Jun. 30, 2023
Carrying amount
Fair value, balance sheet grouping [Line Items]
Long-term debt, fair value	$ 693,483	$ 696,985	$ 855,000
Fair value
Fair value, balance sheet grouping [Line Items]
Long-term debt, fair value	$ 712,852	$ 725,086	$ 862,420

v3.24.2.u1

Debt - Long-Term Debt Outstanding (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023	Jun. 30, 2023
Long-term debt outstanding [Line Items]
Less unamortized debt issuance costs	$ 13,945	$ 15,326	$ 16,382
Total long-term debt	679,538	681,659	839,129
Less current maturities	7,072	7,082	7,082
Net long-term debt	$ 672,466	674,577	832,047
Term loan agreement due on May 31, 2028
Long-term debt outstanding [Line Items]
Weighted Average Interest Rate at June 30, 2024	7.20%
Long-term debt, gross	$ 268,125	271,562	275,000
Revolving credit agreement
Long-term debt outstanding [Line Items]
Weighted Average Interest Rate at June 30, 2024	0.00%
Long-term debt, gross	$ 0	0	155,000
Senior notes due on May 1, 2031
Long-term debt outstanding [Line Items]
Weighted Average Interest Rate at June 30, 2024	7.75%
Long-term debt, gross	$ 425,000	425,000	425,000
Other notes due on January 1, 2061
Long-term debt outstanding [Line Items]
Weighted Average Interest Rate at June 30, 2024	0.00%
Long-term debt, gross	$ 358	$ 423	$ 511

v3.24.2.u1

Debt - Schedule of Debt Maturities (Details) $ in Thousands	Jun. 30, 2024 USD ($)
Debt Disclosure [Abstract]
Remainder of 2024	$ 3,634
2025	10,473
2026	13,750
2027	17,188
2028	223,438
Thereafter	$ 425,000

v3.24.2.u1

Cash flow information (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023
Supplemental Cash Flow Information [Abstract]
Interest paid, net	$ 27,993	$ 24,802
Income taxes paid, net	1,662	558
Right-of-use assets obtained in exchange for new operating lease liabilities	10,844	7,552
Property, plant and equipment additions in accounts payable	5,098	3,359
Equity contribution from Centennial related to the Separation	0	64,724
Equity contribution to MDU Resources for asset/liability transfers related to the Separation	0	(1,548)
MDU Resources' stock issued prior to spin in connection with a business combination	$ 0	$ 383

v3.24.2.u1

Business segment data - Narrative (Details)	Jun. 30, 2024 state
Segment Reporting [Abstract]
Number of states in which entity operates	14

v3.24.2.u1

Business segment data - Information on Segment Data (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Segment Reporting Information [Line Items]
Revenues	$ 806,906	$ 785,189	$ 1,136,496	$ 1,093,089
Operating Segments
Segment Reporting Information [Line Items]
Revenues	806,667	783,664	1,136,111	1,091,720
EBITDA:	167,225	136,831	159,366	127,347
Operating Segments | Pacific
Segment Reporting Information [Line Items]
Revenues	131,827	125,079	210,214	190,722
EBITDA:	17,789	17,457	17,046	17,605
Operating Segments | Northwest
Segment Reporting Information [Line Items]
Revenues	200,225	178,734	319,377	294,654
EBITDA:	50,762	38,871	70,916	52,868
Operating Segments | Mountain
Segment Reporting Information [Line Items]
Revenues	193,769	175,754	253,595	236,372
EBITDA:	43,119	30,323	37,054	26,570
Operating Segments | Central
Segment Reporting Information [Line Items]
Revenues	214,603	231,034	275,565	288,654
EBITDA:	36,188	28,399	17,466	11,500
Operating Segments | Energy Services
Segment Reporting Information [Line Items]
Revenues	66,243	73,063	77,360	81,318
EBITDA:	19,367	21,781	16,884	18,804
Intersegment eliminations
Segment Reporting Information [Line Items]
Revenues	(165,081)	(167,663)	(211,633)	(207,248)
Intersegment eliminations | Pacific
Segment Reporting Information [Line Items]
Revenues	(22,013)	(22,393)	(35,621)	(33,197)
Intersegment eliminations | Northwest
Segment Reporting Information [Line Items]
Revenues	(33,494)	(35,322)	(48,402)	(48,254)
Intersegment eliminations | Mountain
Segment Reporting Information [Line Items]
Revenues	(36,778)	(34,796)	(40,740)	(40,710)
Intersegment eliminations | Central
Segment Reporting Information [Line Items]
Revenues	(55,077)	(61,630)	(61,173)	(68,761)
Intersegment eliminations | Energy Services
Segment Reporting Information [Line Items]
Revenues	(13,447)	(13,706)	(16,428)	(15,928)
Intersegment eliminations | Total reportable segment intersegment operating revenues
Segment Reporting Information [Line Items]
Revenues	$ (160,809)	$ (167,847)	$ (202,364)	$ (206,850)

v3.24.2.u1

Business segment data - Operating Revenues Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ 806,906	$ 785,189	$ 1,136,496	$ 1,093,089
Intersegment operating revenues
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	(165,081)	(167,663)	(211,633)	(207,248)
Corporate, Non-Segment
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	4,511	1,341	9,654	1,767
Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	806,667	783,664	1,136,111	1,091,720
Operating Segments | Total reportable segment operating revenues
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ 967,476	$ 951,511	$ 1,338,475	$ 1,298,570

v3.24.2.u1

Business segment data - EBITDA Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Segment, Reconciliation of Other Items from Segments to Consolidated [Line Items]
Total consolidated net income before income taxes	$ 104,114	$ 76,855	$ 40,160	$ 23,623
Depreciation, depletion and amortization	34,512	31,130	66,724	60,760
Interest expense, net	12,809	17,130	23,955	26,625
Corporate, Non-Segment
Segment, Reconciliation of Other Items from Segments to Consolidated [Line Items]
EBITDA	(15,790)	(11,716)	(28,527)	(16,339)
Operating Segments
Segment, Reconciliation of Other Items from Segments to Consolidated [Line Items]
EBITDA	$ 167,225	$ 136,831	$ 159,366	$ 127,347

v3.24.2.u1

Commitments and contingencies (Details) - USD ($)	Jun. 30, 2024	Dec. 31, 2023	Jun. 30, 2023
Loss Contingencies [Line Items]
Potential liabilities related to litigation and environmental matters	$ 3,200,000	$ 873,000	$ 970,000
Insurance receivables	0	$ 42,000	$ 325,000
Guarantor obligations, maximum exposure, undiscounted	11,500,000
Amount outstanding under guarantees that is reflected on balance sheet	0
Letters of credit set to expire current year	335,000
Letters of credit set to expire in next fiscal year	20,500,000
Letters of credit set to expire, year three	0
Letters of credit set to expire, year four	104,000
Outstanding letters of credit	$ 0
Surety bond expiration period	12 months
Amount of surety bonds outstanding	$ 894,200,000
Letter of Credit
Loss Contingencies [Line Items]
Line of credit facility, maximum borrowing capacity	$ 20,900,000

v3.24.2.u1

Related party transactions (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Related Party Transaction [Line Items]
Selling, general and administrative expenses	$ 59,474	$ 59,450	$ 119,695	$ 108,108
Other income	1,304	2,478	5,054	3,304
Related Party
Related Party Transaction [Line Items]
Selling, general and administrative expenses	413	599	1,200	599
Other income	$ 62	$ 277	$ 138	$ 277
Transition services, period			1 year

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