10-Q

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 10-Q

☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the quarterly period ended September 30, 2023

OR

☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the transition period from _____________ to ______________

Commission file number 1-41642

Knife River Corporation

(Exact name of registrant as specified in its charter)

Delaware	92-1008893
(State or other jurisdiction of incorporation or organization)	(I.R.S. Employer Identification No.)

1150 West Century Avenue

P.O. Box 5568

Bismarck, North Dakota 58506-5568

(Address of principal executive offices)

(Zip Code)

(701) 530-1400

(Registrant's telephone number, including area code)

Securities registered pursuant to Section 12(b) of the Act:

Title of each class	Trading symbol(s)	Name of each exchange on which registered
Common Stock, $0.01 par value	KNF	New York Stock Exchange

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes ☐ No ☒.

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files). Yes ☒ No ☐.

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of "large accelerated filer," "accelerated filer," "smaller reporting company," and "emerging growth company" in Rule 12b-2 of the Exchange Act.

Large Accelerated Filer	☐	Accelerated Filer	☐
Non-Accelerated Filer	☒	Smaller Reporting Company	☐
		Emerging Growth Company	☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). Yes ☐ No ☒.

Indicate the number of shares outstanding of each of the issuer's classes of common stock, as of November 1, 2023: 56,566,214 shares.

1

Index
	Page
Definitions	3
Introduction	4
Part I -- Financial Information
Item 1. Financial Statements	5
Consolidated Statements of Operations -- Three and Nine Months Ended September 30, 2023 and 2022	5
Consolidated Statements of Comprehensive Income -- Three and Nine Months Ended September 30, 2023 and 2022	6
Consolidated Balance Sheets -- September 30, 2023 and December 31, 2022	7
Consolidated Statements of Equity -- Three and Nine Months Ended September 30, 2023 and 2022	8
Consolidated Statements of Cash Flows -- Nine Months Ended September 30, 2023 and 2022	10
Notes to Consolidated Financial Statements	11
1. Background	11
2. Basis of presentation	11
3. Receivables and allowance for expected credit losses	13
4. Inventories	14
5. Earnings per share	14
6. Equity	15
7. Accumulated other comprehensive loss	15
8. Revenue from contracts with customers	17
9. Uncompleted contracts	18
10. Goodwill and other intangible assets	19
11. Fair value measurements	19
12. Debt	21
13. Income taxes	21
14. Cash flow information	22
15. Business segment data	22
16. Employee benefit plans	24
17. Contingencies	24
18. Related-party transactions	25
Item 2. Management's Discussion and Analysis of Financial Condition and Results of Operations	26
Item 3. Quantitative and Qualitative Disclosures About Market Risk	44
Item 4. Controls and Procedures	44
Part II -- Other Information
Item 1. Legal Proceedings	46
Item 1A. Risk Factors	46
Item 2. Unregistered Sales of Equity Securities, Use of Proceeds, and Issuer Purchases of Equity Securities	46
Item 3. Defaults Upon Senior Securities	46
Item 4. Mine Safety Disclosures	46
Item 5. Other Information	46
Item 6. Exhibits	46
Exhibits Index	47
Signatures	48

2

Definitions

The following abbreviations and acronyms used in this Form 10-Q are defined below:

Abbreviation or Acronym
Agency	Publicly-funded work completed for state departments of transportation, as well as cities and counties
ASC	FASB Accounting Standards Codification
CDL	Commercial driver's license
Centennial	Centennial Energy Holdings, Inc., a direct wholly owned subsidiary of MDU Resources and the direct parent company of Knife River prior to the spinoff
Company or Knife River	Knife River Corporation
COVID-19	Coronavirus disease 2019
Distribution	The distribution of approximately 90 percent of the outstanding shares of Knife River common stock to MDU Resources stockholders on a pro rata basis of one share of Knife River common stock for every four shares held of MDU Resources common stock
Dodd-Frank Act	Dodd-Frank Wall Street Reform and Consumer Protection Act
EBITDA	Earnings before interest, taxes, depreciation, depletion and amortization
EDGE	"Competitive EDGE" strategy implemented by the Company to improve margins and to execute on other strategic initiatives aimed at generating long-term profitable growth
Exchange Act	Securities Exchange Act of 1934, as amended
FASB	Financial Accounting Standards Board
GAAP	Accounting principles generally accepted in the United States of America
IIJA	Infrastructure Investment and Jobs Act
Knife River Corporation	The holding company established in conjunction with the Separation and, prior to the Separation, a direct wholly owned subsidiary of MDU Resources
MDU Resources	MDU Resources Group, Inc., the indirect parent company of Knife River prior to the spinoff
SEC	United States Securities and Exchange Commission
Separation	The separation of Knife River from MDU Resources' other businesses and the creation of an independent, publicly traded company
SOFR	Secured Overnight Financing Rate

3

Introduction

Knife River is a leading aggregates-based construction materials and contracting services provider in the United States. The Company's aggregate reserves provide the foundation for its vertically integrated business strategy, with approximately 40 percent of its aggregates in 2023 being used internally to support value-added downstream products (ready-mix concrete and asphalt) and contracting services (heavy-civil construction, asphalt paving, concrete construction, site development and grading services). The Company provides construction materials and contracting services for both public and private customers and is focused on being the provider of choice in mid-size, high-growth markets. Knife River is committed to its plan for continued growth and to delivering for its stakeholders — customers, communities, employees and stockholders — by executing on its four core values: people, safety, quality and the environment.

The Company supplies construction materials to customers in 14 states and also provides related contracting services. It has broad access to high-quality aggregates in most of its markets, which forms the foundation of its vertically integrated business model. Knife River shares resources, including plants, equipment and people, across its various locations to maximize efficiency, and it transports its products by truck, rail and barge to complete the vertical value chain, depending on the particular market. The Company's strategically located aggregate sites, ready-mix plants and asphalt plants, along with its fleet of ready-mix and dump trucks, enables Knife River to better serve its customers. The Company believes its vertically integrated business model is a strong competitive advantage that provides scale, efficiency and operational excellence for the benefit of customers, stockholders and the broader communities that it serves.

The Company is organized into six operating regions: Pacific, Northwest, Mountain, North Central, South and Energy Services. These regions are used to determine the Company's reportable segments, which are based on the Company's method of internal reporting and are aligned by key geographic regions due to the production of construction materials and related contracting services following the seasonal nature of the construction industry. Knife River's reportable segments are: Pacific, Northwest, Mountain and North Central, with South and Energy Services included in the All Other category with its corporate services. The internal reporting of these segments is defined based on the reporting and review process used by the Company's chief executive and chief operating officers. For more information on the Company's business segments, see Note 15 of the Notes to Consolidated Financial Statements.

On May 31, 2023, the Separation of Knife River from MDU Resources was completed as a tax-free spin-off for U.S. federal income tax purposes. As a result of the Separation, MDU Resources distributed shares representing approximately 90 percent of Knife River's outstanding common stock to holders of record of MDU Resources' common stock as of the close of business on May 22, 2023. Following the Distribution, Knife River became an independent, publicly traded company.

4

Part I -- Financial Information

Item 1. Financial Statements

Knife River Corporation
Consolidated Statements of Operations
(Unaudited)
	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2023		2022		2023		2022
	(In thousands, except per share amounts)
Revenue:
Construction materials	$	553,057	$	483,221	$	1,177,726	$	1,060,051
Contracting services	537,315		492,207		1,005,736		937,156
Total revenue	1,090,372		975,428		2,183,462		1,997,207
Cost of revenue:
Construction materials	346,298		340,609		856,606		846,965
Contracting services	474,685		450,332		900,388		861,300
Total cost of revenue	820,983		790,941		1,756,994		1,708,265
Gross profit	269,389		184,487		426,468		288,942
Selling, general and administrative expenses	59,168		41,572		167,276		130,223
Operating income	210,221		142,915		259,192		158,719
Interest expense	15,354		8,817		44,005		21,506
Other income (expense)	7		(1,277)		3,311		(6,056)
Income before income taxes	194,874		132,821		218,498		131,157
Income tax expense	48,219		33,164		56,327		32,947
Net income	$	146,655	$	99,657	$	162,171	$	98,210
Net income per share:
Basic	$	2.59	$	1.76	$	2.87	$	1.74
Diluted	$	2.58	$	1.76	$	2.86	$	1.74
Weighted average common shares outstanding:
Basic	56,566		56,566		56,566		56,566
Diluted	56,735		56,566		56,633		56,566

The accompanying notes are an integral part of these consolidated financial statements.

5

Knife River Corporation
Consolidated Statements of Comprehensive Income
(Unaudited)
	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2023		2022		2023		2022
	(In thousands)
Net income	$	146,655	$	99,657	$	162,171	$	98,210
Other comprehensive income:
Reclassification adjustment for loss on derivative instruments included in net income, net of tax of $— and $27 for the three months ended and $28 and $80 for the nine months ended in 2023 and 2022, respectively	—		82		90		246
Postretirement liability adjustment:
Postretirement liability gains (losses) arising during the period, net of tax of $— and $— for the three months ended and $(6) and $1,879 for the nine months ended in 2023 and 2022, respectively	—		—		(17)		5,820
Amortization of postretirement liability losses included in net periodic benefit cost, net of tax of $16 and $71 for the three months ended and $47 and $213 for the nine months ended in 2023 and 2022, respectively	49		221		144		662
Postretirement liability adjustment	49		221		127		6,482
Other comprehensive income	49		303		217		6,728
Comprehensive income attributable to common stockholders	$	146,704	$	99,960	$	162,388	$	104,938

The accompanying notes are an integral part of these consolidated financial statements.

6

Knife River Corporation
Consolidated Balance Sheets
(Unaudited)
	September 30, 2023		December 31, 2022
Assets	(In thousands, except shares and per share amounts)
Current assets:
Cash, cash equivalents and restricted cash	$	116,159	$	10,090
Receivables, net	491,866		210,157
Costs and estimated earnings in excess of billings on uncompleted contracts	50,545		31,145
Due from related-party	—		16,050
Inventories	314,711		323,277
Prepayments and other current assets	38,094		17,848
Total current assets	1,011,375		608,567
Noncurrent assets:
Property, plant and equipment	2,547,577		2,489,408
Less accumulated depreciation, depletion and amortization	1,248,042		1,174,195
Net property, plant and equipment	1,299,535		1,315,213
Goodwill	274,478		274,540
Other intangible assets, net	11,463		13,430
Operating lease right-of-use assets	44,309		45,873
Investments and other	39,722		36,696
Total noncurrent assets	1,669,507		1,685,752
Total assets	$	2,680,882	$	2,294,319
Liabilities and Stockholders' Equity
Current liabilities:
Long-term debt - current portion	$	7,082	$	211
Related-party notes payable - current portion	—		238,000
Accounts payable	148,977		87,370
Billings in excess of costs and estimated earnings on uncompleted contracts	58,785		39,843
Taxes payable	53,281		8,502
Accrued compensation	37,922		29,192
Due to related-party	—		20,286
Current operating lease liabilities	13,702		13,210
Other accrued liabilities	105,218		80,276
Total current liabilities	424,967		516,890
Noncurrent liabilities:
Long-term debt	675,649		427
Related-party notes payable	—		446,449
Deferred income taxes	173,989		175,804
Noncurrent operating lease liabilities	30,607		32,663
Other	132,652		93,497
Total liabilities	1,437,864		1,265,730
Commitments and contingencies
Stockholders' equity:
Common stock, 300,000,000 shares authorized, $0.01 par value, 56,997,350 shares issued and 56,566,214 shares outstanding at September 30, 2023; 80,000 shares authorized, issued and outstanding, $10 par value at December 31, 2022	570		800
Other paid-in capital	613,024		549,106
Retained earnings	645,185		494,661
MDU Resources common stock held by subsidiary at cost - 538,921 shares at December 31, 2022	—		(3,626)
Treasury stock held at cost - 431,136 shares	(3,626)		—
Accumulated other comprehensive loss	(12,135)		(12,352)
Total stockholders' equity	1,243,018		1,028,589
Total liabilities and stockholders' equity	$	2,680,882	$	2,294,319

The accompanying notes are an integral part of these consolidated financial statements.

7

Knife River Corporation
Consolidated Statements of Equity
(Unaudited)
	Common Stock			Other Paid-in Capital		Retained Earnings		MDU Resources' Stock Held by Subsidiary			Treasury Stock			Accumula-ted Other Comprehe-nsive Loss
	Shares	Amount						Shares	Amount		Shares	Amount				Total
	(In thousands, except shares)
At December 31, 2022	80,000	$	800	$	549,106	$	494,661	(538,921)	$	(3,626)	—	$	—	$	(12,352)	$	1,028,589
Net loss	—	—		—		(41,320)		—	—		—	—		—		(41,320)
Other comprehensive income	—	—		—		—		—	—		—	—		93		93
Stock-based compensation	—	—		453		(39)		—	—		—	—		—		414
Net transfers to Centennial	—	—		(1,385)		(11,622)		—	—		—	—		—		(13,007)
At March 31, 2023	80,000	$	800	$	548,174	$	441,680	(538,921)	$	(3,626)	—	$	—	$	(12,259)	$	974,769
Net income	—	—		—		56,836		—	—		—	—		—		56,836
Other comprehensive Income	—	—		—		—		—	—		—	—		75		75
Stock-based compensation	—	—		212		14		—	—		—	—		—		226
Transfer of MDU Resources' stock held by subsidiary	—	—		—		—		538,921	3,626		—	—		—		3,626
Receipt of treasury stock at cost	—	—		—		—		—	—		(431,136)	(3,626)		—		(3,626)
Retirement of historical common stock in connection with the Separation	(80,000)	(800)		800		—		—	—		—	—		—		—
Issuance of common stock in connection with the Separation	56,997,350	570		(596)		—		—	—		—	—		—		(26)
Net transfers from Centennial and MDU Resources including Separation adjustments	—	—		62,972		—		—	—		—	—		—		62,972
At June 30, 2023	56,997,350	$	570	$	611,562	$	498,530	—	$	—	(431,136)	$	(3,626)	$	(12,184)	$	1,094,852
Net income	—	—		—		146,655		—	—		—	—		—		146,655
Other comprehensive income	—	—		—		—		—	—		—	—		49		49
Stock-based compensation	—	—		1,462		—		—	—		—	—		—		1,462
At September 30, 2023	56,997,350	$	570	$	613,024	$	645,185	—	$	—	(431,136)	$	(3,626)	$	(12,135)	$	1,243,018

The accompanying notes are an integral part of these consolidated financial statements.

8

Knife River Corporation
Consolidated Statements of Equity
(Unaudited)
	Common Stock			Other Paid-in Capital		Retained Earnings		MDU Resources' Stock Held by Subsidiary			Treasury Stock			Accumula-ted Other Comprehe-nsive Loss
	Shares	Amount						Shares	Amount		Shares	Amount				Total
	(In thousands, except shares)
At December 31, 2021	80,000	$	800	$	549,714	$	430,446	(538,921)	$	(3,626)	—	$	—	$	(24,490)	$	952,844
Net loss	—	—		—		(40,010)		—	—		—	—		—		(40,010)
Other comprehensive income	—	—		—		—		—	—		—	—		303		303
Stock-based compensation	—	—		333		(27)		—	—		—	—		—		306
Net transfers to Centennial	—	—		(3,432)		(12,976)		—	—		—	—		—		(16,408)
At March 31, 2022	80,000	$	800	$	546,615	$	377,433	(538,921)	$	(3,626)	—	$	—	$	(24,187)	$	897,035
Net income	—	—		—		38,562		—	—		—	—		—		38,562
Other comprehensive income	—	—		—		—		—	—		—	—		6,122		6,122
Stock-based compensation	—	—		333		(27)		—	—		—	—		—		306
Net transfers to Centennial	—	—		(5,063)		(12,974)		—	—		—	—		—		(18,037)
At June 30, 2022	80,000	$	800	$	541,885	$	402,994	(538,921)	$	(3,626)	—	$	—	$	(18,065)	$	923,988
Net income	—	—		—		99,657		—	—		—	—		—		99,657
Other comprehensive income	—	—		—		—		—	—		—	—		303		303
Stock-based compensation	—	—		134		(11)		—	—		—	—		—		123
Net transfers (from) to Centennial	—	—		220		(12,975)		—	—		—	—		—		(12,755)
At September 30, 2022	80,000	$	800	$	542,239	$	489,665	(538,921)	$	(3,626)	—	$	—	$	(17,762)	$	1,011,316

The accompanying notes are an integral part of these consolidated financial statements.

9

Knife River Corporation
Consolidated Statements of Cash Flows
(Unaudited)
	Nine Months Ended
	September 30,
	2023		2022
	(In thousands)
Operating activities:
Net income	$	162,171	$	98,210
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion and amortization	92,511		88,551
Deferred income taxes	(1,884)		5,043
Provision for credit losses	1,386		(296)
Amortization of debt issuance costs	2,425		355
Employee stock-based compensation costs	2,127		800
Pension and postretirement benefit plan net periodic benefit cost	889		981
Unrealized (gains) losses on investments	(685)		3,172
Gains on sales of assets	(3,806)		(3,575)
Changes in current assets and liabilities, net of acquisitions:
Receivables	(302,536)		(239,565)
Due from related-party	16,050		1,258
Inventories	8,566		(18,624)
Other current assets	(20,127)		835
Accounts payable	91,663		69,552
Due to related-party	(7,310)		9,829
Other current liabilities	78,006		21,786
Pension and postretirement benefit plan contributions	(1,611)		(313)
Other noncurrent changes	35,092		1,400
Net cash provided by operating activities	152,927		39,399
Investing activities:
Capital expenditures	(86,450)		(121,840)
Acquisitions, net of cash acquired	—		450
Net proceeds from sale or disposition of property and other	5,227		5,716
Investments	(1,764)		(2,226)
Net cash used in investing activities	(82,987)		(117,900)
Financing activities:
Issuance of current related-party notes, net	—		100,000
Issuance of long-term related-party notes, net	205,275		26,872
Issuance of long-term debt	700,000		—
Repayment of long-term debt	(1,891)		(206)
Debt issuance costs	(16,640)		(749)
Proceeds from issuance of common stock	(26)		—
Net transfers to Centennial	(850,589)		(42,236)
Net cash provided by financing activities	36,129		83,681
Increase in cash, cash equivalents and restricted cash	106,069		5,180
Cash, cash equivalents and restricted cash -- beginning of year	10,090		13,848
Cash, cash equivalents and restricted cash -- end of period	$	116,159	$	19,028

The accompanying notes are an integral part of these consolidated financial statements.

10

Knife River Corporation

Notes to Consolidated

Financial Statements

September 30, 2023 and 2022

(Unaudited)

Note 1 - Background

On August 4, 2022, MDU Resources announced that its board of directors approved a plan to pursue the Separation of Knife River from MDU Resources. On May 31, 2023, the Separation was completed by a pro rata distribution of shares representing approximately 90 percent of Knife River's outstanding common stock to MDU Resources' stockholders. MDU Resources' stockholders received one share of Knife River common stock for every four shares of MDU Resources common stock held as of the close of business on May 22, 2023. MDU Resources retained approximately 10 percent of Knife River's common stock. The Distribution was tax-free to its stockholders for U. S. federal income tax purposes. At the time of the Separation, the net parent investment in Knife River held by Centennial was settled between the companies. As a result of the Separation, Knife River is now an independent public company trading on the New York Stock Exchange under the symbol "KNF." More information on the Separation and Distribution, as well as the Company's historical results, can be found within the Company's Registration Statement on Form 10.

Note 2 - Basis of presentation

The accompanying consolidated interim financial statements were prepared in accordance with 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 Registration Statement on Form 10. 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.

On May 31, 2023, the Company became a stand-alone publicly traded company. Prior to the Separation on May 31, 2023, Knife River operated as a wholly owned subsidiary of Centennial and an indirect, wholly owned subsidiary of MDU Resources and not as a stand-alone company. These consolidated financial statements and footnotes reflect the historical financial position, results of operations and cash flows of the Company as historically managed within MDU Resources for the periods prior to the completion of the Separation and reflect the financial position, results of operations and cash flows as a stand-alone company for the period after the completion of the Separation. The historical consolidated financial statements and footnotes were prepared on a “carve-out” basis in connection with the Separation and were derived from the consolidated financial statements of MDU Resources as if the Company operated on a stand-alone basis during the periods presented, and were prepared utilizing the legal entity approach in conformity with GAAP. The results for the three and nine months ended September 30, 2022, vary from the previously reported MDU Resources' construction materials and contracting services segment due to an adjustment to a cost allocation for interim periods to conform with the Company's current year accounting. This adjustment does not impact the historical annual financial statements included in the Company's Registration Statement on Form 10. This adjustment increased cost of revenue for the three months ended September 30, 2022, by $4.4 million ($3.4 million after tax) and decreased cost of revenue for the nine months ended September 30, 2022, by $1.6 million ($1.2 million after tax). The adjustment is not considered material for the three or nine months ended September 30, 2022.

The Company utilized allocations and carve-out methodologies to prepare its historical consolidated financial statements and footnotes. The consolidated financial statements and footnotes herein may not be indicative of the Company's future performance or actual expenses that would have been incurred as a stand-alone company for the periods presented.

All revenues and costs, as well as assets and liabilities, directly associated with the business activity of the Company 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 (expense). There were no amounts allocated to Knife River for the three months ended September 30, 2023, and $8.7 million was allocated for the nine months ended September 30, 2023. For the three and nine months ended September 30, 2022, there was $3.8 million and $13.4 million, respectively, allocated to Knife River. These expenses have been allocated to the Company 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 are 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.

11

Prior to the Separation, Knife River historically participated in Centennial’s centralized cash management program, including its overall financing arrangements. This arrangement is not reflective of the manner in which the Company would have been able to finance its operations had it been independent from MDU Resources for the period prior to the completion of the Separation. Knife River had related-party note agreements in place with Centennial for the financing of its capital needs, which are reflected as related-party notes payable on the Consolidated Balance Sheets as of December 31, 2022. The related-party notes payable to Centennial at May 30, 2023, was $889.7 million. As part of the Separation, Centennial made an equity contribution to the Company to release the Company of its obligation related to the outstanding notes payable. Also as part of the Separation, the Company entered into debt agreements and subsequently paid a dividend of $825.0 million from the debt proceeds to Centennial, which Centennial used to repay a portion of the Company's outstanding indebtedness. These transactions resulted in the Company receiving a net equity contribution of $64.7 million and is reflected as "Net transfers from Centennial and MDU Resources including separation adjustments" in the Consolidated Statement of Equity. Interest expense in the Consolidated Statements of Operations includes the allocation of interest on borrowing and funding associated with the related-party note agreements for periods prior to the Separation.

Prior to the Separation, income tax expense and tax balances in the consolidated financial statements were calculated on a separate tax return basis. The separate tax return method applies the accounting guidance for income taxes to the standalone financial statements as if the Company were a separate taxpayer and a standalone enterprise. Management believes the assumptions supporting the allocation and presentation of income taxes on a separate return basis are reasonable. As a stand-alone entity, the Company will file tax returns on its own behalf, and tax balances and effective income tax rate may differ from the amounts reported in the historical periods.

Management has also evaluated the impact of events occurring after September 30, 2023, up to the date of issuance of these consolidated interim financial statements on November 6, 2023, that would require recognition or disclosure in the Consolidated Financial Statements.

Principles of consolidation

For the pre-Separation periods, the accompanying financial statements of the Company were derived from the consolidated financial statements and accounting records of MDU Resources as if the Company and its wholly owned subsidiaries operated on a stand-alone basis during the periods presented. The consolidated financial statements were prepared in accordance with GAAP and include the accounts of the Company and its wholly owned subsidiaries. All intercompany accounts and transactions between the businesses comprising the Company have been eliminated in the accompanying consolidated financial statements. Related-party transactions between the Company and MDU Resources or Centennial for general operating activities and intercompany debt have been included in the consolidated financial statements for the pre-Separation periods. These related-party transactions were settled in cash and are reflected in the pre-Separation Consolidated Balance Sheets as “Due from related-party” or “Due to related-party” with the aggregate net effect reflected in the Consolidated Statements of Cash Flows within operating activities and “Related-party notes payable” with the aggregate net effect reflected in the Consolidated Statements of Cash Flows within financing activities.

The aggregate net effect of related-party transactions not settled in cash as part of the Separation have been reflected in the pre-Separation Consolidated Balance Sheet within “Other paid-in capital”. See Note 18 for additional information on related-party transactions.

Use of estimates

The preparation of financial statements in conformity with GAAP requires the Company 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 the Company 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.

New accounting standards

There have been no recent accounting standards that are expected to materially affect the Company.

Cash, cash equivalents and restricted cash

The Company considers all highly liquid investments with an original maturity of three months or less, when purchased, to be cash and cash equivalents. At September 30, 2023, the $116.2 million of cash, cash equivalents and restricted cash on the Consolidated Statements of Cash Flows is comprised of $84.0 million of cash and cash equivalents and $32.2 million of restricted cash. At September 30, 2022, the Company did not have any restricted cash. Restricted cash represents deposits held by Knife

12

River's captive insurance company that is required by state insurance regulations to remain in the captive insurance company as cash.

Seasonality of operations

Some of the Company's 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 the Company as a whole, may not be indicative of results for the full fiscal year or other future periods.

Note 3 - 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 the Company's receivables are due in 30 days or less. The total balance of receivables past due 90 days or more was $14.4 million and $11.2 million at September 30, 2023 and December 31, 2022, respectively. Receivables were as follows:

	September 30, 2023		December 31, 2022
	(In thousands)
Trade receivables	$	236,373	$	104,347
Contract receivables	223,874		82,428
Retention receivables	37,814		28,859
Receivables, gross	498,061		215,634
Less expected credit loss	6,195		5,477
Receivables, net	$	491,866	$	210,157

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. The Company develops and documents its methodology to determine its allowance for expected credit losses. Risk characteristics used by the Company 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		North Central		All Other		Total
	(In thousands)
At December 31, 2022	$	2,045	$	1,253	$	1,278	$	839	$	62	$	5,477
Current expected credit loss provision	45		313		164		(89)		(1)		432
Less write-offs charged against the allowance	1		68		18		—		—		87
At March 31, 2023	$	2,089	$	1,498	$	1,424	$	750	$	61	$	5,822
Current expected credit loss provision	9		74		631		(132)		1		583
Less write-offs charged against the allowance	18		512		3		—		2		535
At June 30, 2023	$	2,080	$	1,060	$	2,052	$	618	$	60	$	5,870
Current expected credit loss provision	46		242		(152)		215		20		371
Less write-offs charged against the allowance	26		4		13		3		—		46
At September 30, 2023	$	2,100	$	1,298	$	1,887	$	830	$	80	$	6,195

13

	Pacific		Northwest		Mountain		North Central		All Other		Total
	(In thousands)
At December 31, 2021	$	2,052	$	512	$	1,610	$	1,152	$	80	$	5,406
Current expected credit loss provision	1		(125)		(130)		6		(5)		(253)
Less write-offs charged against the allowance	1		20		3		1		1		26
At March 31, 2022	$	2,052	$	367	$	1,477	$	1,157	$	74	$	5,127
Current expected credit loss provision	11		58		(17)		(37)		(3)		12
Less write-offs charged against the allowance	—		56		4		47		2		109
At June 30, 2022	$	2,063	$	369	$	1,456	$	1,073	$	69	$	5,030
Current expected credit loss provision	(6)		194		(111)		(141)		9		(55)
Less write-offs charged against the allowance	9		7		40		4		16		76
At September 30, 2022	$	2,048	$	556	$	1,305	$	928	$	62	$	4,899

Note 4 - Inventories

Inventories on the Consolidated Balance Sheets were as follows:

	September 30, 2023		December 31, 2022
	(In thousands)
Finished products	$	213,702	$	211,496
Raw materials	63,156		78,571
Supplies and parts	37,853		33,210
Total	$	314,711	$	323,277

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 the Company's 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.

Note 5 - Earnings per share

The calculation for basic and diluted earnings per share for any period presented prior to the Separation are based on the number of shares outstanding on May 31, 2023, the Separation and Distribution date. For periods prior to the Separation, it is assumed that there are no dilutive equity instruments as there were no Knife River stock-based awards outstanding at the time.

Basic earnings per share is computed by dividing net income by the weighted average number of shares of common stock outstanding during the applicable period. Diluted earnings 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 restricted stock units. Weighted average common shares outstanding is comprised of issued shares of 56,997,350 less shares held in treasury of 431,136, as described in Note 6. Basic and diluted earnings 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				Nine Months Ended
	September 30,				September 30,
	2023		2022		2023		2022
	(In thousands, except per share amounts)
Net income	$	146,655	$	99,657	$	162,171	$	98,210
Weighted average common shares outstanding - basic	56,566		56,566		56,566		56,566
Effect of dilutive restricted stock units	169		—		67		—
Weighted average common shares outstanding - diluted	56,735		56,566		56,633		56,566
Shares excluded from the calculation of diluted earnings per share	—		—		—		—
Net income per share - basic	$	2.59	$	1.76	$	2.87	$	1.74
Net income per share - diluted	$	2.58	$	1.76	$	2.86	$	1.74

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Note 6 - Equity

On May 31, 2023, the Company issued 56,997,350 shares of common stock with a par value of $0.01 in connection with the Separation.

The Company historically held 538,921 shares of MDU Resources common stock through one of its subsidiaries. The historical shares are presented as MDU Resources' stock held by subsidiary on the Consolidated Statement of Equity. In connection with the Separation, Knife River entered into an agreement with MDU Resources to transfer the stock of MDU Resources held by its subsidiary to MDU Resources in exchange for 431,136 shares of Knife River common stock. The number of shares transferred to Knife River was based on the value of the stock at the time of the Separation. The historical MDU Resources common stock held by subsidiary at cost of $3.6 million at September 30, 2023, on the Consolidated Balance Sheets reflects the value of the MDU Resources common stock at the time it was granted to Knife River's subsidiary and will remain at the historical value since the exchange was between related parties. The 431,136 shares of Knife River common stock are presented as Treasury stock held at cost in the Consolidated Balance Sheet and reduce the number of common stock shares outstanding.

Stock-based compensation

Prior to the Separation, key employees of the Company participated in various stock-based compensation plans authorized and managed by MDU Resources. All awards granted under the plans were based on MDU Resources' common shares, however, Knife River recognized the expense for its participants in its financial statements.

At the time of the Separation, each outstanding MDU Resources time-vested restricted stock unit and performance share award held by a Knife River employee was converted into Knife River time-vested restricted stock units. The converted awards will continue to vest over the original vesting period, which is generally three years from the grant date. All performance share awards that were converted at the time of the Separation were first adjusted using a combined performance factor based on MDU Resources' actual performance as of December 31, 2022. The number of restricted stock units was determined by taking the closing per share price of MDU Resources on May 31, 2023, and dividing by the closing per share price of Knife River on June 1, 2023. The ratio used to convert the MDU Resources' share-based awards was designed to preserve the aggregate intrinsic value of the award immediately after the Separation when compared to the aggregate intrinsic value of the award immediately prior to the Separation. The existing unvested stock-based awards issued through MDU Resources' stock-based compensation plans were modified in connection with the Separation to maintain an equivalent value immediately before and after Separation. The impact of this modification will be recorded over the remaining vesting periods and was not material to the Company's stock-based compensation expense for the three or nine months ended September 30, 2023.

Note 7 - 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)
At 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)
Other comprehensive loss before reclassification	—		—		—
Amounts reclassified from accumulated other comprehensive loss	—		49		49
Net current-period other comprehensive income	—		49		49
At September 30, 2023	$	—	$	(12,135)	$	(12,135)

15

	Net Unrealized Loss on Derivative  Instruments  Qualifying as Hedges		Postretirement  Liability Adjustment		Total Accumulated  Other Comprehensive  Loss
	(In thousands)
At December 31, 2021	$	(418)	$	(24,072)	$	(24,490)
Amounts reclassified from accumulated other comprehensive loss	82		221		303
Net current-period other comprehensive income	82		221		303
At March 31, 2022	$	(336)	$	(23,851)	$	(24,187)
Other comprehensive income before reclassification	—		5,820		5,820
Amounts reclassified from accumulated other comprehensive loss	82		220		302
Net current-period other comprehensive income	82		6,040		6,122
At June 30, 2022	$	(254)	$	(17,811)	$	(18,065)
Amounts reclassified from accumulated other comprehensive loss	82		221		303
Net current-period other comprehensive income	82		221		303
At September 30, 2022	$	(172)	$	(17,590)	$	(17,762)

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				Nine Months Ended				Location on Consolidated Statements of Operations
	September 30,				September 30,
	2023		2022		2023		2022
	(In thousands)
Reclassification adjustment for loss on derivative income	$	—	$	(109)	$	(118)	$	(326)	Interest expense
	—		27		28		80		Income taxes
	—		(82)		(90)		(246)
Amortization of postretirement liability losses included in net periodic benefit cost	(65)		(292)		(191)		(875)		Other income
	16		71		47		213		Income taxes
	(49)		(221)		(144)		(662)
Total reclassifications	$	(49)	$	(303)	$	(234)	$	(908)

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Note 8 - 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. The Company is considered an agent for certain taxes collected from customers. As such, the Company presents 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. The Company believes 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 15.

Three Months Ended September 30, 2023	Pacific		Northwest		Mountain		North Central		All Other		Total
	(In thousands)
Aggregates	$	33,624	$	57,398	$	39,519	$	47,656	$	15,388	$	193,585
Ready-mix concrete	39,861		46,785		44,053		73,183		12,157		216,039
Asphalt	14,050		43,462		59,673		95,053		10,539		222,777
Other	81,081		4,497		11		10,211		118,312		214,112
Contracting services public-sector	32,632		68,316		135,700		181,779		23,483		441,910
Contracting services private-sector	17,745		25,144		43,944		8,526		46		95,405
Internal sales	(37,566)		(36,683)		(68,178)		(111,288)		(39,741)		(293,456)
Revenues from contracts with customers	$	181,427	$	208,919	$	254,722	$	305,120	$	140,184	$	1,090,372

Three Months Ended September 30, 2022	Pacific		Northwest		Mountain		North Central		All Other		Total
	(In thousands)
Aggregates	$	28,695	$	52,614	$	31,258	$	45,039	$	14,197	$	171,803
Ready-mix concrete	35,395		45,600		37,334		64,496		16,082		198,907
Asphalt	10,935		45,110		45,553		96,830		7,133		205,561
Other	63,002		4,447		12		8,711		90,539		166,711
Contracting services public-sector	30,529		78,664		100,298		184,266		18,874		412,631
Contracting services private-sector	14,512		20,424		38,755		5,664		221		79,576
Internal sales	(30,710)		(42,627)		(49,089)		(110,700)		(26,635)		(259,761)
Revenues from contracts with customers	$	152,358	$	204,232	$	204,121	$	294,306	$	120,411	$	975,428

Nine Months Ended September 30, 2023	Pacific		Northwest		Mountain		North Central		All Other		Total
	(In thousands)
Aggregates	$	79,768	$	147,937	$	78,051	$	81,999	$	35,767	$	423,522
Ready-mix concrete	106,531		125,273		92,929		139,369		33,604		497,706
Asphalt	21,640		84,908		89,955		141,942		22,888		361,333
Other	168,104		11,513		21		22,703		193,528		395,869
Contracting services public-sector	53,450		138,621		244,320		280,853		61,293		778,537
Contracting services private-sector	37,220		80,258		94,706		13,884		1,131		227,199
Internal sales	(75,345)		(84,937)		(108,888)		(167,055)		(64,479)		(500,704)
Revenues from contracts with customers	$	391,368	$	503,573	$	491,094	$	513,695	$	283,732	$	2,183,462

17

Nine Months Ended September 30, 2022	Pacific		Northwest		Mountain		North Central		All Other		Total
	(In thousands)
Aggregates	$	72,088	$	129,752	$	67,388	$	75,718	$	40,892	$	385,838
Ready-mix concrete	98,520		121,079		84,950		124,026		46,959		475,534
Asphalt	26,909		79,801		77,021		141,595		19,886		345,212
Other	143,140		11,804		26		20,766		152,757		328,493
Contracting services public-sector	63,450		141,783		202,495		275,797		52,933		736,458
Contracting services private-sector	38,922		60,321		91,783		8,809		863		200,698
Internal Sales	(76,911)		(84,733)		(90,654)		(162,342)		(60,386)		(475,026)
Revenues from contracts with customers	$	366,118	$	459,807	$	433,009	$	484,369	$	253,904	$	1,997,207

Note 9 - 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:

	September 30, 2023		December 31, 2022		Change		Location on Consolidated Balance Sheets
	(In thousands)
Contract assets	$	50,545	$	31,145	$	19,400	Costs and estimated earnings in excess of billings on uncompleted contracts
Contract liabilities	(58,785)		(39,843)		(18,942)		Billings in excess of costs and estimated earnings on uncompleted contracts
Net contract liabilities	$	(8,240)	$	(8,698)	$	458

The Company recognized $3.4 million and $35.1 million in revenue for the three and nine months ended September 30, 2023, respectively, which was previously included in contract liabilities at December 31, 2022. The Company recognized $3.0 million and $29.2 million in revenue for the three and nine months ended September 30, 2022, respectively, which was previously included in contract liabilities at December 31, 2021.

The Company recognized a net increase in revenues of $12.1 million and $10.6 million for the three and nine months ended September 30, 2023, respectively, from performance obligations satisfied in prior periods. The Company recognized a net increase in revenues of $4.9 million and $10.4 million for the three and nine months ended September 30, 2022, respectively, from performance obligations satisfied in prior periods.

Remaining performance obligations

The remaining performance obligations, also referred to as backlog, include unrecognized revenues that the Company reasonably expects 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 the Company's contracts for contracting services have an original duration of less than one year.

At September 30, 2023, the Company's remaining performance obligations were $732.2 million. The Company expects to recognize the following revenue amounts in future periods related to these remaining performance obligations: $677.7 million within the next 12 months or less; $38.5 million within the next 13 to 24 months; and $16.0 million in 25 months or more.

18

Note 10 - Goodwill and other intangible assets

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

	Balance at January 1, 2023		Goodwill Acquired During the Year		Measurement Period Adjustments		Balance at September 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
All Other	42,528		—		—		42,528
Total	$	274,540	$	—	$	(62)	$	274,478

Other amortizable intangible assets were as follows:

	September 30, 2023		December 31, 2022
	(In thousands)
Customer relationships	$	18,540	$	18,540
Less accumulated amortization	8,668		7,367
	9,872		11,173
Noncompete agreements	4,039		4,039
Less accumulated amortization	3,358		2,985
	681		1,054
Other	2,479		5,279
Less accumulated amortization	1,569		4,076
	910		1,203
Total	$	11,463	$	13,430

Amortization expense for amortizable intangible assets for the three and nine months ended September 30, 2023, was $647,000 and $2.0 million, respectively. Amortization expense for amortizable intangible assets for the three and nine months ended September 30, 2022, was $729,000 and $2.1 million, respectively. Estimated amortization expense for identifiable intangible assets as of September 30, 2023, was:

	Remainder of 2023		2024		2025		2026		2027		Thereafter
	(In thousands)
Amortization expense	$	590	$	2,157	$	2,042	$	1,739	$	1,717	$	3,218

Note 11 - 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 ASC 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.

The Company measures its investments in certain fixed-income and equity securities at fair value with changes in fair value recognized in income. The Company anticipates using these investments, which consist of insurance contracts, to satisfy its obligations under its unfunded, nonqualified defined benefit and defined contribution plans for the Company's 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 $23.5 million and $20.1 million at September 30, 2023 and December 31, 2022, respectively, are classified as investments on the Consolidated Balance Sheets. The net unrealized loss on these investments was $597,000 for the three months ended September 30, 2023 and the net unrealized gain on these investments was $685,000 for the nine months ended September 30, 2023. The net unrealized loss on these investments was $541,000 and $3.2 million for the three and nine months ended September 30, 2022, 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.

As part of the Separation, the Company retired certain insurance contracts used to satisfy its obligations under its unfunded, nonqualified defined contribution plan for the Company's executive officers and certain key management employees. The proceeds of the retired contracts totaled $4.8 million, which were used to purchase life insurance policies and re-invested in fixed-income and equity securities in the third quarter of 2023.

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

	Fair Value Measurements at September 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 September 30, 2023
	(In thousands)
Assets:
Money market funds	$	—	$	3,199	$	—	$	3,199
Insurance contracts*	—		23,483		—		23,483
Total assets measured at fair value	$	—	$	26,682	$	—	$	26,682

*    The insurance contracts invest approximately 41 percent in fixed-income investments, 19 percent in cash equivalents, 18 percent in common stock of large-cap companies, 8 percent in common stock of mid-cap companies, 8 percent target date investments, 5 percent in common stock of small-cap companies and 1 percent in international investments.

	Fair Value Measurements at December 31, 2022, 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, 2022
	(In thousands)
Assets:
Money market funds	$	—	$	2,448	$	—	$	2,448
Insurance contracts*	—		20,083		—		20,083
Total assets measured at fair value	$	—	$	22,531	$	—	$	22,531

*    The insurance contracts invest approximately 63 percent in fixed-income investments, 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, 6 percent in target date investments and 2 percent in cash equivalents.

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 are 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 the Company believes 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.

The Company applies the provisions of the fair value measurement standard to its 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. The Company reviews the carrying value of its long-lived assets, excluding goodwill, whenever events or changes in circumstances indicate that such carrying amounts may not be recoverable.

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:

	September 30, 2023
	(In thousands)
Carrying amount	$	698,747
Fair value	$	700,687

The carrying amounts of the Company's remaining financial instruments included in current assets and current liabilities approximate their fair values.

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Note 12 - Debt

Certain debt instruments of the Company contain restrictive covenants and cross-default provisions. In order to borrow under the debt agreements, the Company must be in compliance with the applicable covenants and certain other conditions, all of which management believes the Company, as applicable, was in compliance with at September 30, 2023. In the event the Company does not comply with the applicable covenants and other conditions, alternative sources of funding may need to be pursued.

On April 25, 2023, the Company issued $425.0 million of 7.75 percent senior notes due May 1, 2031, pursuant to an indenture.

On May 31, 2023, the Company entered into a senior secured credit agreement consisting of a $275.0 million term loan and a $350.0 million revolving credit facility. As of September 30, 2023, the Company had no outstanding borrowings against the revolving credit facility. Each debt facility has a SOFR-based interest rate and a maturity date of May 31, 2028. The term loan has a mandatory annual amortization of 2.50 percent for years one and two, 5.00 percent for years three and four, and 7.50 percent in the fifth year. The agreement contains customary covenants and provisions, including a covenant of Knife River not to permit, at any time, the ratio of total debt to trailing twelve month EBITDA to be greater than 4.75 to 1.00. The agreement also contains an interest coverage ratio covenant stating that Knife River’s trailing twelve month EBITDA to interest expense is to be no less than 2.25 to 1.00. The covenants also include restrictions on the sale of certain assets, loans and investments.

Knife River's wholly owned subsidiary companies, subject to certain exclusions and exceptions, are named as subsidiary guarantors of the senior notes and the senior secured credit agreement. In addition, Knife River has pledged substantially all of its assets as collateral, subject to certain exclusions and exceptions, for the senior secured credit agreement.

Long-term debt

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

	Weighted Average Interest Rate at September 30, 2023		September 30, 2023
			(In thousands)
Term loan agreement due on May 31, 2028	7.52	%	$	273,281
Senior notes due on May 1, 2031	7.75	%	425,000
Other notes due on January 1, 2061	—	%	466
Less unamortized debt issuance costs			16,016
Total long-term debt			682,731
Less current maturities			7,082
Net long-term debt			$	675,649

Schedule of Debt Maturities Long-term debt maturities, which excludes unamortized debt issuance costs, at September 30, 2023, were as follows:

	Remainder of 2023		2024		2025		2026		2027		Thereafter
	(In thousands)
Long-term debt maturities	$	1,719	$	7,082	$	10,520	$	13,802	$	17,187	$	648,437

Note 13 - Income taxes

Post-Separation, the income tax provisions are calculated based on Knife River's operating footprint, as well as tax return elections and assertions. Current income tax liabilities including amounts for unrecognized tax benefits related to the Company's activities included in MDU Resources' income tax returns were deemed to be immediately settled with MDU Resources' final settlement allocation process as dictated by the MDU Resources' Tax Sharing Agreement.

Prior to the Separation, income tax expense and tax balances in the consolidated financial statements were calculated on a separate tax return basis. The separate tax return method applies the accounting guidance for income taxes to the stand-alone financial statements as if the Company were a separate taxpayer and a stand-alone enterprise. Management believes the assumptions supporting the allocation and presentation of income taxes on a separate return basis are reasonable. As a stand-alone entity, the Company will file tax returns on its own behalf, and tax balances and effective income tax rate may differ from the amounts reported in the historical periods.

Income tax expense is based on reported income before income taxes. Deferred income taxes reflect the tax effect of temporary differences between asset and liability amounts that are recognized for financial reporting purposes and the amounts that are recognized for income tax purposes. These deferred taxes are measured by applying currently enacted tax laws.

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Valuation allowances are recognized to reduce deferred tax assets to the amount that will more likely than not be realized. In assessing the need for a valuation allowance, management considers all available evidence for each jurisdiction including past operating results, estimates of future taxable income and the feasibility of ongoing tax planning strategies and actions. When there is a change in determination as to the amount of deferred tax assets that can be realized, the valuation allowance is adjusted with a corresponding impact to provision for income taxes in the period in which such determination is made.

The Company's cash tax payments for the year may vary significantly from prior years as a result of the timing of the Separation and the seasonality of the Company's business.

Other Tax Matters

Tax Matters Agreement In connection with the Separation, the Company entered into a tax matters agreement with MDU Resources. The tax matters agreement governs the respective rights, responsibilities, and obligations between the Company and MDU Resources after the Separation with respect to tax liabilities and benefits, tax attributes, tax returns, tax contests and other tax sharing regarding U.S. federal, state and local income taxes, other tax matters and related tax returns.

Tax Refunds and Attributes The tax matters agreement provides for the allocation of certain pre-closing tax attributes between the Company and MDU Resources. Tax attributes will be allocated in accordance with the principles set forth in the MDU Resources' Tax Sharing Agreement, then existing, unless otherwise required by law. Under the tax matters agreement, the Company will be entitled to refunds for taxes for which the Company is responsible.

Note 14 - Cash flow information

Cash expenditures for interest and income taxes were as follows:

	Nine Months Ended
	September 30,
	2023		2022
	(In thousands)
Interest paid, net	$	32,028	$	19,472
Income taxes paid, net	$	22,183	$	23,163

Noncash investing and financing transactions were as follows:

	Nine Months Ended
	September 30,
	2023		2022
	(In thousands)
Right-of-use assets obtained in exchange for new operating lease liabilities	$	9,717	$	5,851
Property, plant and equipment additions in accounts payable	$	2,832	$	4,884
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	$	—

Note 15 - Business segment data

The Company focuses on the vertical integration of its products and services by offering customers a single source for construction materials and related contracting services. The Company operates in 14 states across the United States. Its operating segments include: Pacific, Northwest, Mountain, North Central, South and Energy Services. The operating segments are organized by geographic region in the United States due to the cyclical nature of the construction work performed. The Company’s reportable segments are those that are based on the Company’s method of internal reporting and management of the business and are Pacific, Northwest, Mountain and North Central. The South and Energy Services operating segments do not meet the criteria to be reportable segments and, as such, are combined with its corporate services in All Other. Each segment is led by a segment president that reports to the Company’s chief operating officer. The chief operating officer works directly with the chief executive officer, the chief operating decision maker, to evaluate the performance of the segments using EBITDA and the allocation of resources.

All of the reportable segments mine, process and sell construction aggregates (crushed stone and sand and gravel); produce and sell asphalt; and produce and sell ready-mix concrete, as well as in some segments the sale of merchandise and other building materials and related services, as well as vertically integrating their contracting services to support the aggregate-based product lines including heavy-civil construction, asphalt and concrete paving, and site development and grading, and in some segments the manufacturing of prestressed concrete products. The Pacific segment and All Other also produce and sell liquid asphalt products and the Pacific segment sells cement. Although not common to all locations, within All Other is the sale of merchandise and other building materials and related services.

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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 Registration Statement on Form 10. Information on the Company's segments was as follows:

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2023		2022		2023		2022
	(In thousands)
External operating revenues:
Pacific	$	181,427	$	152,358	$	391,368	$	366,118
Northwest	208,919		204,232		503,573		459,807
Mountain	254,722		204,121		491,094		433,009
North Central	305,120		294,306		513,695		484,369
All Other	140,184		120,411		283,732		253,904
Total external operating revenues	$	1,090,372	$	975,428	$	2,183,462	$	1,997,207
Intersegment operating revenues:
Pacific	$	37,566	$	30,710	$	75,345	$	76,911
Northwest	36,683		42,627		84,937		84,733
Mountain	68,178		49,089		108,888		90,654
North Central	111,288		110,700		167,055		162,342
All Other	39,741		26,635		64,479		60,386
Total intersegment operating revenues	$	293,456	$	259,761	$	500,704	$	475,026
EBITDA:
Pacific	$	37,558	$	24,563	$	56,486	$	45,194
Northwest	48,867		43,797		102,711		79,774
Mountain	60,473		39,644		86,486		60,244
North Central	70,508		58,584		71,402		50,424
All Other	23,994		5,500		35,323		5,578
Total segment EBITDA	$	241,400	$	172,088	$	352,408	$	241,214

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

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2023		2022		2023		2022
	(In thousands)
Total reportable segment operating revenues	$	1,203,903	$	1,088,143	$	2,335,955	$	2,157,943
Other operating revenues	179,925		147,046		348,211		314,290
Less:
Elimination of intersegment operating revenues	293,456		259,761		500,704		475,026
Total consolidated operating revenues	$	1,090,372	$	975,428	$	2,183,462	$	1,997,207

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

	Three Months Ended				Nine Months Ended
	Sept. 30,				Sept. 30,
	2023		2022		2023		2022
	(In thousands)
Total EBITDA for reportable segments	$	217,406	$	166,588	$	317,085	$	235,636
Other EBITDA	23,994		5,500		35,323		5,578
Less:
Depreciation, depletion and amortization	31,752		30,450		92,511		88,551
Interest expense, net*	14,774		8,817		41,399		21,506
Total consolidated income before income taxes	$	194,874	$	132,821	$	218,498	$	131,157
*Interest, net is interest expense net of interest income.

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Note 16 - Employee benefit plans

The Company has noncontributory qualified defined benefit pension plans and other postretirement benefit plans for certain eligible employees. Prior to the Separation, Knife River was a participant in the MDU Resources postretirement benefit plan. The Company historically treated its share of the postretirement obligation under that plan as a single employer plan in accordance with ASC 715 - Compensation - Retirement Benefits and recorded the funded status and net periodic benefit cost associated with Knife River employees at Knife River. In connection with the Separation, effective June 1, 2023, Knife River established a new, stand-alone postretirement plan comparable to that of MDU Resources and transferred its obligations of $1.5 million for current participants (inclusive of employees that transferred to the Company from MDU Resources) to that plan. The Company's pension benefit plans were stand-alone for Knife River prior to the Separation.

Components of net periodic benefit cost for the Company's pension benefit plans were as follows:

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2023		2022		2023		2022
	(In thousands)
Components of net periodic benefit cost:
Interest cost	$	408	$	282	$	1,224	$	846
Expected return on assets	(450)		(493)		(1,350)		(1,479)
Amortization of net actuarial loss	128		214		384		642
Net periodic benefit cost	$	86	$	3	$	258	$	9

Components of net periodic benefit cost for the Company's other postretirement benefit plans were as follows:

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2023		2022		2023		2022
	(In thousands)
Components of net periodic benefit cost:
Service cost	$	91	$	131	$	270	$	393
Interest cost	180		128		541		384
Expected return on assets	—		(3)		12		(9)
Amortization of prior service credit	(20)		(20)		(60)		(60)
Amortization of net actuarial (gain) loss	(43)		88		(132)		264
Net periodic benefit cost	$	208	$	324	$	631	$	972

The components of net periodic benefit cost, other than the service cost component, are included in other income on the Consolidated Statements of Operations. The service cost component is included in selling, general and administrative expenses on the Consolidated Statements of Operations.

Note 17 - 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. The Company accrues 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. The Company does 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, the Company discloses 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 September 30, 2023 and December 31, 2022, the Company accrued contingent liabilities as a result of litigation, which have not been discounted, of $645,000 and $1.0 million, respectively. At December 31, 2022, the Company also recorded corresponding insurance receivables of $325,000 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. The Company 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

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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 Company's environmental matters that were previously reported in the audited financial statements and notes included in the Company's Registration Statement on Form 10.

Guarantees

Certain subsidiaries of the Company 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 September 30, 2023, 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 September 30, 2023.

Certain subsidiaries of the Company have outstanding letters of credit to third parties related to insurance policies, cement purchases and other agreements. At September 30, 2023, the fixed maximum amounts guaranteed under these letters of credit aggregated $4.8 million. At September 30, 2023, the amounts of scheduled expiration of the maximum amounts guaranteed under these letters of credit aggregate to $4.0 million in 2023 and $771,000 in 2024. There were no amounts outstanding under the previously mentioned letters of credit at September 30, 2023.

In the normal course of business, the Company has surety bonds related to contracts for contracting services, reclamation obligations and insurance policies of its subsidiaries. In the event a subsidiary of the Company 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 is expected to expire within the next 12 months; however, the Company will likely continue to enter into surety bonds for its subsidiaries in the future. At September 30, 2023, approximately $619.2 million of surety bonds were outstanding, which were not reflected on the Consolidated Balance Sheet.

Note 18 - Related-party transactions

Transition services agreements

As part of the Separation, MDU Resources is providing transition services to the Company and the Company is providing transition services to MDU Resources in accordance with the Transition Services Agreement entered into on May 30, 2023. For the three and nine months ended September 30, 2023, the Company paid $1.3 million and $1.9 million, respectively, related to these activities, which were reflected in selling, general and administrative expenses on the Consolidated Statements of Operations. For the three and nine months ended September 30, 2023, the Company received $407,000 and $684,000, respectively, related to these activities, which were reflected in other income (expense) on the Consolidated Statements of Operations. The majority of the transition services are expected to be completed over a period of one year, but no longer than two years after the Separation.

Related-party notes payable

The related-party notes payable to Centennial at May 30, 2023, was $889.7 million. As part of the Separation, Centennial made an equity contribution to the Company to release the Company of its obligation related to the outstanding notes payable. Also as part of the Separation, the Company issued $425.0 million of 7.75 percent senior notes due May 1, 2031, a credit agreement consisting of a $275.0 million term loan and a $350.0 million revolving credit facility, of which $190.0 million was drawn down at the time of the Separation. On May 31, 2023, the Company paid a dividend of $825.0 million from these proceeds to Centennial, which Centennial used to repay a portion of the Company's outstanding indebtedness. These transactions resulted in the Company receiving a net equity contribution of $64.7 million and is reflected as "Net transfers from Centennial and MDU Resources including separation adjustments" in the Consolidated Statement of Equity. Refer to Note 12 for additional information on the debt facilities entered into in connection with the Separation.

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

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Item 2. Management's Discussion and Analysis of Financial Condition and Results of Operations

Knife River is a people-first construction materials and contracting services company. The Company provides construction materials and contracting services to build safe roads, bridges and airport runways that connect people with where they want to go and with the supplies they need. Knife River also champions a positive workplace culture by focusing on safety, training, inclusion, compensation and work-life balance.

Knife River is one of the leading providers of crushed stone and sand and gravel in the United States and operates through six regions: Pacific, Northwest, Mountain, North Central, South and Energy Services, with operations across 14 states. These regions are used to determine the Company's reportable segments and are based on the Company's method of internal reporting and management of the business. The Company's reportable segments are: Pacific, Northwest, Mountain, and North Central, with South and Energy Services included in All Other with its corporate services. The segments primarily provide aggregates, asphalt and ready-mix concrete, as well as related contracting services such as heavy-civil construction, asphalt paving, concrete delivery and paving, site development and grading.

As a leading aggregates-based construction materials and contracting services provider in the United States, the Company's 1.1 billion tons of aggregate reserves provide the foundation for a vertically integrated business strategy, with approximately 40 percent of its aggregates in 2023 being used internally to support value-added downstream products (ready-mix concrete and asphalt) and contracting services (heavy-civil construction, asphalt paving, concrete construction, site development and grading services, and in some segments the manufacturing of prestressed concrete products). Its aggregate sites and associated asphalt and ready-mix plants are primarily in strategic locations near mid-sized, high-growth markets, providing Knife River with a transportation advantage for its materials that supports competitive pricing and increased margins. Knife River provides its products and services to both public and private markets, with public markets tending to be more stable across economic cycles, which helps offset the cyclical nature of the private markets.

The Company provides various products and services and operates a variety of facility types, including aggregate quarries and mines, ready-mix concrete plants, asphalt plants and distribution facilities. The Company operates in the following states:

•Pacific: Alaska, California and Hawaii

•Northwest: Oregon and Washington

•Mountain: Idaho, Montana and Wyoming

•North Central: Iowa, Minnesota, North Dakota and South Dakota

•All Other: Iowa, Nebraska, North Dakota, South Dakota, Texas and Wyoming

The following table presents a summary of products and services provided, as well as modes of transporting those products:

	Products and Services							Modes of Transportation
					Precast/
			Ready-Mix	Construction	Prestressed	Liquid		Heavy
	Aggregates	Asphalt	Concrete	Services	Concrete	Asphalt	Cement	Equipment	Trucking	Rail	Barge
Pacific	X	X	X	X	X	X	X	X	X	X	X
Northwest	X	X	X	X	X			X	X	X	X
Mountain	X	X	X	X				X	X
North Central	X	X	X	X	X			X	X	X
All Other	X	X	X	X		X		X	X	X	X

The Separation

On August 4, 2022, MDU Resources announced that its board of directors approved a plan to pursue the Separation of Knife River from MDU Resources. On May 31, 2023, the Separation was completed by a pro rata distribution of shares representing approximately 90 percent of Knife River's outstanding common stock to MDU Resources' stockholders. MDU Resources' stockholders received one share of Knife River common stock for every four shares of MDU Resources common stock held as of the close of business on May 22, 2023. MDU Resources retained approximately 10 percent of Knife River's common stock. The Distribution was tax-free to its stockholders for U. S. federal income tax purposes. At the time of the Separation, the net parent investment in Knife River held by Centennial was settled between the companies. As a result of the Separation, Knife River is now an independent public company trading on the New York Stock Exchange under the symbol "KNF." More information on the Separation and Distribution, as well as the Company's historical results, can be found within the Company's Registration Statement on Form 10.

Forward-Looking Statements

This Quarterly Report on Form 10-Q contains forward-looking statements within the meaning of Section 21E of the Exchange Act. Forward-looking statements are all statements other than statements of historical fact, including without limitation those statements that are identified by the words "anticipates," "estimates," "expects," "intends," "plans," "predicts" and similar expressions, and include statements concerning plans, trends, objectives, goals, strategies, future events or performance, and underlying assumptions (many of which are based, in turn, upon further assumptions) and other statements that are other than

26

statements of historical facts. From time to time, the Company may publish or otherwise make available forward-looking statements of this nature, including statements related to EDGE, that are contained within the Market Conditions and Outlook and Business Segment Financial and Operating Data sections.

Forward-looking statements involve risks and uncertainties, which could cause actual results or outcomes to differ materially from those expressed. The Company's expectations, beliefs and projections are expressed in good faith and are believed by the Company to have a reasonable basis, including without limitation, management's examination of historical operating trends, data contained in the Company's records and other data available from third parties. Nonetheless, the Company's expectations, beliefs or projections may not be achieved or accomplished and changes in such assumptions and factors could cause actual future results to differ materially.

Any forward-looking statement contained in this document speaks only as of the date on which the statement is made, and the Company undertakes no obligation to update any forward-looking statement or statements to reflect events or circumstances that occur after the date on which the statement is made or to reflect the occurrence of unanticipated events, except as required by law. New factors emerge from time to time, and it is not possible for management to predict all the factors, nor can it assess the effect of each factor on the Company's business or the extent to which any factor, or combination of factors, may cause actual results to differ materially from those contained in any forward-looking statement. All forward-looking statements, whether written or oral and whether made by or on behalf of the Company, are expressly qualified by the risk factors and cautionary statements reported in the section entitled "Risk Factors" in the Company's Registration Statement on Form 10 and subsequent filings with the SEC.

Basis of Presentation

Knife River historically operated as a wholly owned subsidiary of Centennial and an indirect, wholly owned subsidiary of MDU Resources and not as a stand-alone company until the Separation from MDU Resources was completed. The accompanying historical consolidated financial statements and footnotes, which were prepared on a “carve-out” basis in connection with the Separation, were derived from the consolidated financial statements of MDU Resources as if the Company operated on a stand-alone basis during the historical periods presented, and were prepared utilizing the legal entity approach in conformity with GAAP. For additional information related to the basis of presentation, see Note 2.

Prior to the Separation, Knife River historically participated in Centennial’s centralized cash management program, including its overall financing arrangements. Knife River had related-party note agreements in place with Centennial for the financing of its capital needs, which are reflected as related-party notes payable on the Consolidated Balance Sheet at December 31, 2022. Interest expense in the Consolidated Statements of Operations reflects the allocation of interest on borrowing and funding associated with the related-party note agreements. Upon the completion of the Separation, Knife River implemented its own financing agreements with lenders. For additional information on the Company's current debt financing, see Note 12.

All intercompany balances and transactions between the businesses comprising Knife River have been eliminated in the accompanying consolidated financial statements.

Market Conditions and Outlook

Knife River’s markets remain resilient and construction activity remains generally strong despite general and economic challenges, such as transportation disruptions, supply-chain constraints, inflation and higher interest rates. With approximately 80 percent of its contracting revenue from public-sector projects, Knife River has been able to balance the cyclical nature of its private-sector customers. While Knife River experienced inflationary pressures in the past year, price increases have generally outpaced the increased costs. For more information on factors that may negatively impact Knife River's business, see the section entitled "Risk Factors" in the Company's Registration Statement on Form 10.

Backlog. Knife River’s contracting services backlog was as follows:

	September 30, 2023		September 30, 2022
	(In millions)
Pacific	$	69.8	$	79.1
Northwest	227.4		150.6
Mountain	251.1		310.9
North Central	109.3		181.1
All Other	74.6		82.0
	$	732.2	$	803.7

27

Expected margins on backlog at September 30, 2023, were greater than the expected margins on backlog at September 30, 2022. Approximately 83 percent of the Company's backlog at September 30, 2023, relates to publicly funded projects, including street and highway construction projects, which are driven primarily by public works projects for state departments of transportation. Period-over-period increases or decreases cannot be used as an indicator of future revenues, net income or EBITDA. While the Company believes the current backlog of work remains firm, prolonged delays in the receipts of critical supplies and materials or continued increases to pricing, among other things, could result in customers seeking to delay or terminate existing or pending agreements and could reduce expected margins. See the section entitled “Risk Factors” in the Company's Registration Statement on Form 10 for a list of factors that can cause revenues to be realized in periods and at levels that are different from originally projected.

Public Funding. Funding for public projects is dependent on federal and state funding, such as appropriations to the Federal Highway Administration. The American Rescue Plan Act enacted in the first quarter of 2021 provides $1.9 trillion in COVID-19 relief funding for states, schools and local governments. States are moving forward with allocating these funds based on federal criteria and state needs, and in some cases, funding of infrastructure projects could positively impact Knife River. Additionally, the IIJA was enacted in the fourth quarter of 2021 and is providing long-term opportunities by designating $131 billion in funding across Knife River’s footprint. IIJA funding has been making its way to the 14 states where Knife River operates, with a total of nearly $80 billion having been allocated to specific projects in those states as of August 2023. In addition to federal funding, 12 out of the 14 states in which Knife River operates have implemented new funding mechanisms for public projects, including projects related to highways, airports and other public infrastructure. Knife River continues to monitor the implementation and impact of these legislative items.

Profitability. Knife River’s management continually monitors its margins and has been proactive in applying strategies to address the inflationary impacts seen across the United States. In 2023, the Company began implementing EDGE to improve margins and to execute on other strategic initiatives aimed at generating long-term profitable growth. The EDGE acronym stands for EBITDA Margin Improvement, Discipline, Growth and Excellence. As part of this strategy, Knife River has increased its product pricing over the past year and is targeting higher-margin bidding opportunities. In addition, the Company has established dedicated teams that assist with implementing cost-savings initiatives to further enhance its gross margin.

Knife River operates in geographically diverse and competitive markets, and strives to maximize efficiencies, including transportation costs and economies of scale, to maintain strong margins. Its margins can experience negative pressure from competition, as well as impacts from the volatility in the cost of raw materials, such as diesel fuel, gasoline, natural gas, liquid asphalt, cement and steel, with fuel and liquid asphalt costs often having the most significant impact on results. Many of these raw materials are subject to factors that are beyond the control of the Company, including global economic and political events and new and changing governmental regulations. The energy services business is particularly susceptible to volatility in liquid asphalt costs, which can impact both cost of sales and revenues, for which the Company cannot reliably predict future pricing. Such volatility and inflationary pressures may have an impact on the Company’s margins, including fixed-price contracting services contracts that are particularly vulnerable to the volatility of energy and material prices. The Company mitigates its exposure to these fluctuations by entering into various purchase commitments, as well as by generally including terms in the Company's contracting services agreements that provide for price adjustments related to variations in raw materials costs.

Knife River's operations can also be significantly impacted by both favorable and unfavorable weather conditions. Unseasonably wet and/or cold weather in the states where it operates can delay the start or cause an early end to the construction season or cause temporary delays on specific projects, while unseasonably dry or warm weather in the states where it operates can allow for an early start to construction season or allow for early completions on specific projects. Either of these conditions can impact both its construction materials sales and contracting services revenues. In early 2023, the Company saw record levels of precipitation in the western part of the United States, which caused work to be delayed until later in the year. During the third quarter, the Company largely caught up on this work, as reflected in the Pacific segment results of operations. Other variables that can impact Knife River’s margins include the timing of project starts or completions, and declines or delays in new and existing projects due to the cyclical nature of the construction industry. Accordingly, operating results in any particular period may not be indicative of the results that can be expected for any other period.

Workforce. As a people-first company, Knife River continually takes steps to address the challenge of recruitment and retention of employees. To help attract new workers to the construction industry and enhance the skills of its current employees, Knife River operates a state-of-the-art training facility. The Knife River Training Center offers hands-on training for construction-related careers, including heavy-equipment operators and truck drivers in addition to safety and leadership training. One of the most popular courses is CDL training, which is helping to address some of the recent labor shortages and trends. Through September 30, 2023, training center staff have provided 18 entry-level driver's training sessions for 141 CDL students since opening in 2022, including seven classes for 55 students in 2023. Students graduating from the Knife River CDL program have had a 98 percent success rate earning their CDLs.

Today’s labor market includes an aging workforce and labor shortages, including shortages of truck drivers, which has caused increased labor-related costs. Knife River continues to monitor the labor markets and assess additional opportunities to enhance and support its workforce. Despite these efforts, Knife River expects labor costs to continue to increase.

28

Consolidated Overview

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2023		2022		2023		2022
	(In millions)
Revenue	$	1,090.4	$	975.4	$	2,183.5	$	1,997.2
Cost of revenue	821.0		790.9		1,757.0		1,708.3
Gross profit	269.4		184.5		426.5		288.9
Selling, general and administrative expenses	59.2		41.6		167.3		130.2
Operating income	210.2		142.9		259.2		158.7
Interest expense	15.3		8.8		44.0		21.5
Other income (expense)	—		(1.3)		3.3		(6.1)
Income before income taxes	194.9		132.8		218.5		131.1
Income tax expense	48.2		33.1		56.3		32.9
Net income	$	146.7	$	99.7	$	162.2	$	98.2
EBITDA*	$	241.4	$	172.1	$	352.4	$	241.2
Adjusted EBITDA*	$	247.5	$	173.1	$	360.0	$	247.6

*EBITDA and Adjusted EBITDA are non-GAAP financial measures. For more information and reconciliations to the nearest GAAP measures, see the section entitled "Non-GAAP Financial Measures."

Revenue includes revenue from the sale of construction materials and contracting services. Revenue for construction materials is recognized at a point in time when delivery of the products has taken place. Contracting services revenue is recognized over time using an input method based on the cost-to-cost measure of progress on a project.

Cost of revenue includes all material, labor and overhead costs incurred in the production process for Knife River's products and services. These costs are impacted by various drivers, the most significant of which includes changes in raw material costs, energy costs and salary and benefits costs. Cost of revenue also includes depreciation, depletion and amortization attributable to the assets used in the production process.

Gross profit includes revenue less cost of revenue, as defined above, and is the difference between revenue and the cost of making a product or providing a service, before deducting selling, general and administrative expenses, income taxes and interest expense.

Selling, general and administrative expenses include the costs for estimating, bidding and business development, as well as costs related to corporate functions. Selling expenses can vary depending on the volume of projects in process and the number of employees assigned to estimating and bidding activities. Other general and administrative expenses include outside services; information technology; depreciation and amortization; training, travel and entertainment; office supplies; allowance for expected credit losses; gains or losses on the sale of assets; and other miscellaneous expenses.

Other income (expense) includes net periodic benefit costs for the Company’s benefit plan expenses, other than service costs; interest income; realized and unrealized gains and losses on investments for the Company’s nonqualified benefit plans; earnings or losses on joint venture arrangements; and other miscellaneous income or expenses.

Income tax expense consists of corporate income taxes related to the sale of the Company's products and services. The effective tax rate can be affected by many factors, including changes in tax laws, regulations or rates, new interpretations of existing laws or regulations and changes to the Company's overall levels of income before income tax.

The discussion that follows focuses on the key financial measures the Company uses to evaluate the performance of its business, which include revenue, gross profit, gross margin, EBITDA and EBITDA margin. Gross margin is calculated by dividing gross profit by revenue. Gross margin reflects the percentage of revenue earned in comparison to cost. EBITDA and EBITDA margin are non-GAAP financial measures. For more information and reconciliations to the nearest GAAP measures, see the section entitled "Non-GAAP Financial Measures."

29

The following tables summarize operating results for the Company.

	Three Months Ended						Nine Months Ended
	September 30,						September 30,
	2023			2022			2023			2022
	Amount		% of Revenues	Amount		% of Revenues	Amount		% of Revenues	Amount		% of Revenues
	(In millions)
Revenues by operating segment:
Pacific	$	181.4		$	152.4		$	391.4		$	366.1
Northwest	209.4			204.7			504.2			461.2
Mountain	255.1			204.1			491.5			433.0
North Central	305.1			294.3			513.7			484.4
All Other and internal sales	139.4			119.9			282.7			252.5
Total revenues	$	1,090.4		$	975.4		$	2,183.5		$	1,997.2
Gross profit by operating segment:
Pacific	$	42.8	23.6%	$	27.4	18.0%	$	71.7	18.3%	$	54.0	14.7%
Northwest	50.6		24.1%	44.1		21.5%	109.3		21.7%	82.4		17.9%
Mountain	60.7		23.8%	40.9		20.0%	89.3		18.2%	64.6		14.9%
North Central	74.5		24.4%	58.9		20.0%	82.8		16.1%	55.7		11.5%
All Other	40.8		29.3%	13.2		11.0%	73.4		25.9%	32.2		12.7%
Total gross profit	$	269.4	24.7%	$	184.5	18.9%	$	426.5	19.5%	$	288.9	14.5%
EBITDA*:
Pacific	$	37.6	20.7%	$	24.6	16.1%	$	56.5	14.4%	$	45.2	12.3%
Northwest	48.9		23.3%	43.8		21.4%	102.7		20.4%	79.8		17.3%
Mountain	60.4		23.7%	39.6		19.4%	86.5		17.6%	60.2		13.9%
North Central	70.5		23.1%	58.6		19.9%	71.4		13.9%	50.4		10.4%
All Other	24.0		17.2%	5.5		4.6%	35.3		12.5%	5.6		2.2%
Total EBITDA*	$	241.4	22.1%	$	172.1	17.6%	$	352.4	16.1%	$	241.2	12.1%

*EBITDA, segment EBITDA, EBITDA margin and segment EBITDA margin are non-GAAP financial measures. For more information and a reconciliation to the nearest GAAP measure, see the section entitled "Non-GAAP Financial Measures."

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2023		2022		2023		2022
Sales (thousands):
Aggregates (tons)	12,022		12,399		26,071		26,891
Ready-mix concrete (cubic yards)	1,271		1,306		2,944		3,179
Asphalt (tons)	3,349		3,550		5,441		5,968
Average selling price:*
Aggregates (per ton)	$	16.10	$	13.86	$	16.24	$	14.35
Ready-mix concrete (per cubic yard)	$	169.98	$	152.34	$	169.02	$	149.59
Asphalt (per ton)	$	66.51	$	57.91	$	66.41	$	57.85

*The average selling price includes freight and delivery and other revenues.

30

	Three Months Ended						Nine Months Ended
	September 30,						September 30,
	2023			2022			2023			2022
	Amount		% of Revenues	Amount		% of Revenues	Amount		% of Revenues	Amount		% of Revenues
	(In millions)
Revenues by product line:
Aggregates	$	193.6		$	171.8		$	423.5		$	385.8
Ready-mix concrete	216.0			198.9			497.7			475.5
Asphalt	222.8			205.6			361.3			345.2
Other*	214.1			166.7			395.9			328.5
Contracting services	537.3			492.2			1,005.8			937.2
Internal sales	(293.4)			(259.8)			(500.7)			(475.0)
Total revenues	$	1,090.4		$	975.4		$	2,183.5		$	1,997.2
Gross profit by product line:
Aggregates	$	51.8	26.7%	$	32.7	19.1%	$	90.6	21.4%	$	62.8	16.3%
Ready-mix concrete	37.7		17.4%	34.4		17.3%	74.5		15.0%	67.0		14.1%
Asphalt	39.4		17.7%	29.2		14.2%	49.7		13.8%	35.4		10.3%
Other*	77.9		36.4%	46.3		27.8%	106.3		26.9%	47.8		14.6%
Contracting services	62.6		11.7%	41.9		8.5%	105.4		10.5%	75.9		8.1%
Total gross profit	$	269.4	24.7%	$	184.5	18.9%	$	426.5	19.5%	$	288.9	14.5%

*Other includes cement, liquid asphalt, merchandise, fabric and spreading, and other products and services that individually are not considered to be a core line of business.

Three Months Ended September 30, 2023, Compared to Three Months Ended September 30, 2022

Revenue

Revenue improved $115.0 million as pricing momentum across the core product lines was supported by continued demand, increased market pricing and EDGE-related pricing initiatives. The increased pricing added $90.9 million in revenue. The Company also saw strong demand in the Mountain region, which contributed $40.6 million to its increased contracting services revenues. Partially offsetting these increases were decreased asphalt, aggregate and ready-mix concrete sales volumes of $25.3 million as a result of the Company continuing to target improved bid margins and the partial sale of non-strategic assets in southeast Texas in December 2022.

Gross profit and gross margin

Gross profit improved $84.9 million and gross margin improved 580 basis points. This increase was primarily driven by higher sales prices outpacing costs across all product lines by $39.0 million, largely as a result of market pricing and EDGE-related initiatives, including operating efficiencies and pricing optimization. Higher contracting services margins contributed $20.8 million in gross profit, which was related to improved bid margins, job productivity gains and higher revenues in the Mountain region during the quarter. Additionally, the Company benefited from higher liquid asphalt margins driven by favorable sales price increases, primarily market pricing; cost improvements; and higher sales volumes. Lower overall equipment operating costs, including fuel, also had a positive impact in the quarter.

Selling, general and administrative expenses

Selling, general and administrative expenses increased $17.6 million. As a result of the Separation from MDU Resources, the Company experienced increased recurring costs including payroll-related costs of $6.7 million, largely due to additional staff and stock-based compensation expense for the management team and board of directors; higher insurance costs of $1.2 million; and higher professional services of $600,000, which were offset by a reduction in general corporate expenses from MDU Resources of $3.8 million, as discussed in Note 2. Also, as part of the Separation, the Company incurred one-time costs of $4.4 million, which were offset in part by income from the transition services agreement of $407,000. Further contributing to higher selling, general and administrative costs were increased payroll-related costs of $7.1 million mainly due to higher incentive accruals based on the Company's performance, higher office expenses of $600,000 and increased expected credit losses directly associated with an increase in receivable balances over 90 days and the absence of bad debt recoveries in 2022.

Interest expense

Interest expense increased $6.5 million due primarily to higher average interest rates. Interest rates were higher as a result of the Company settling related-party notes payable as part of the Separation and entering into new debt arrangements, which resulted in additional interest expense in the period of $9.4 million. Partially offsetting the increase was lower average debt balances. For additional information, see Notes 12 and 18.

31

Other income (expense)

Other income improved $1.3 million due in part to increased interest income on higher cash balances of $600,000; income resulting from the transition services agreement with MDU Resources of $400,000, as discussed in Note 18; and improved returns on the Company's nonqualified benefit plan investments.

Income tax expense

Income tax expense increased $15.1 million corresponding with higher income before income taxes.

Nine Months Ended September 30, 2023, Compared to Nine Months Ended September 30, 2022

Revenue

Revenue improved $186.3 million as pricing momentum across all product lines and regions was supported by demand, increased market pricing and EDGE-related pricing initiatives. The increased pricing added $187.9 million in revenue. The Company also saw increased contracting services revenue, primarily from strong demand in the Mountain region and more available work in the Northwest region. Partially offsetting these increases were decreased ready-mix concrete, asphalt and aggregate sales volumes of $87.8 million, primarily attributable to the absence in 2023 of certain impact projects, lower internal sales volumes resulting from the strategy to target improved bid margins, project timing and the partial sale of non-strategic assets in southeast Texas in December 2022.

Gross profit and gross margin

Gross profit improved $137.6 million and gross margin improved 500 basis points. Higher sales prices outpacing costs across its product lines contributed $66.6 million in gross profit, which was largely as a result of increased market pricing and EDGE-related initiatives, including operating efficiencies and pricing optimization. Higher contracting services margins contributed $29.5 million to gross profit, primarily related to improved bid margins, job productivity gains and higher revenues in the Mountain region. Additionally, the energy services business benefited from higher liquid asphalt margins driven by favorable sales price increases, primarily market pricing; cost improvements; and higher sales volumes. Lower overall equipment operating costs, including fuel, also had a positive impact during the year.

Selling, general and administrative expenses

Selling, general and administrative expenses increased $37.1 million. As a result of the Separation from MDU Resources, the Company experienced increased recurring costs including payroll-related costs of $8.6 million, largely due to additional staff and stock-based compensation expense for the management team and board of directors; insurance costs of $2.3 million; and professional services of $900,000, which were offset in part by a reduction in general corporate expenses from MDU Resources of $4.7 million, as discussed in Note 2. Also, as part of the Separation, the Company incurred one-time costs of $7.1 million, primarily related to professional services, insurance costs and the transition services agreement with MDU Resources, which is offset in part by income from the transition services agreement of $684,000. Further contributing to higher selling, general and administrative costs were increased payroll-related costs of $16.6 million, due in part to higher incentive accruals based on the Company's performance; higher office expenses of $1.9 million; higher information technology; and increased expected credit losses of $1.7 million directly associated with an increase in receivable balances over 90 days and the absence of bad debt recoveries in 2022.

Interest expense

Interest expense increased $22.5 million due primarily to higher average interest rates. Interest rates were higher as a result of the Company settling related-party notes payable as part of the Separation and entering into new debt arrangements, which resulted in additional interest expense in the period of $23.4 million. Partially offsetting the increase was lower average debt balances. For additional information, see Notes 12 and 18.

Other income (expense)

Other income increased $9.4 million due in part to improved returns on nonqualified benefit plan investments of $5.8 million; increased interest income of $2.6 million on higher cash balances and on the cash held in escrow for the $425.0 million of senior notes issued prior to the completion of the Separation; and income resulting from the transition services agreement with MDU Resources, as discussed in Note 18.

Income tax expense

Income tax expense increased $23.4 million corresponding with higher income before income taxes.

Business Segment Financial and Operating Data

A discussion of key financial data from Knife River’s business segments follows. This discussion is focused on the key financial measures the Company uses to evaluate the performance of its business from a segment level, which include revenue, gross profit, gross margin, EBITDA and EBITDA margin. Knife River focuses on gross margin, which is defined as gross profit as a percent of revenue, as a key metric when assessing the performance of the business as management believes that analyzing changes in costs in relation to changes in revenue provides more meaningful insight into the results of operations than examining costs in isolation. EBITDA and EBITDA margin are non-GAAP financial measures. For more information and reconciliations to the nearest GAAP measure, see the section entitled "Non-GAAP Financial Measures.”

32

Results of Operations - Pacific

	Three Months Ended							Nine Months Ended
	September 30,							September 30,
	2023			2022			% Change	2023			2022			% Change
	(In millions)
Revenue	$	181.4		$	152.4		19%	$	391.4		$	366.1		7%
Gross profit	$	42.8		$	27.4		56%	$	71.7		$	54.0		33%
Gross margin	23.6		%	18.0		%		18.3		%	14.7		%
EBITDA	$	37.6		$	24.6		53%	$	56.5		$	45.2		25%
EBITDA margin	20.7		%	16.1		%		14.4%			12.3		%

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2023		2022		2023		2022
	(In millions)
Revenues:
Aggregates	$	33.6	$	28.7	$	79.7	$	72.1
Ready-mix concrete	39.9		35.4		106.5		98.5
Asphalt	14.0		10.9		21.7		26.9
Other*	81.1		63.0		168.1		143.1
Contracting services	50.4		45.1		90.7		102.4
Internal sales	(37.6)		(30.7)		(75.3)		(76.9)
	$	181.4	$	152.4	$	391.4	$	366.1

*Other includes cement, liquid asphalt, merchandise, fabric and spreading, and other products that individually are not considered to be a core line of business for the segment.

Three Months Ended September 30, 2023, Compared to Three Months Ended September 30, 2022

Revenue

Revenue improved $29.0 million, largely as project work delayed by weather in the first quarter created additional volumes for asphalt products and aggregates, as well as increased workloads for the associated contracting services. Revenue increased $10.2 million for aggregates, cement and ready-mix concrete as a result of price increases to cover rising costs, increased sales of higher priced products and market improvements. Also contributing to the increase were strong cement product sales volumes to third-party customers in Alaska and strong aggregate and ready-mix concrete sales volumes of $2.9 million from increased demand in Hawaii as the local economy continues to regain momentum for Agency and residential work. Higher demand for ready-mix concrete products in northern California from an acquisition in December 2022 also had a positive impact on the quarter. These increases were offset somewhat by lower asphalt products pricing of $3.1 million due to lower liquid asphalt prices.

Gross profit and gross margin

Gross profit improved $15.4 million and gross margin improved 560 basis points, largely the result of increased volumes across all product lines contributing an additional $9.9 million in gross profit and increased pricing outpacing higher costs, as previously discussed.

EBITDA and EBITDA margin

EBITDA improved $13.0 million and EBITDA margin improved 460 basis points. These increases were the direct result of the previously discussed higher gross profit, partially offset by higher selling, general and administrative costs of $2.5 million. The increase in selling, general and administrative costs includes higher payroll-related costs of $1.6 million, largely related to higher incentive accruals based on the Company's performance; increased insurance costs of $200,000; and higher professional service fees and other miscellaneous expenses.

Nine Months Ended September 30, 2023, Compared to Nine Months Ended September 30, 2022

Revenue

Revenue improved $25.3 million. Revenue across most product lines was higher as prices increased to cover rising costs and markets improved, together adding $28.8 million of revenue. Third-party cement product sales volumes also increased due to higher Agency and residential demand. In addition, the economic environment in Hawaii continued to regain momentum during the second and third quarters contributing additional aggregate and ready-mix sales volumes of $13.1 million. Partially offsetting the increased revenues was the absence in 2023 of an impact project in California of $10.9 million that affected contracting services workloads as well as asphalt volumes. Also, lower aggregate and ready-mix sales volumes experienced earlier in the year for work delayed by wet weather conditions in California, were offset in part by the significant progress made on this work during the third quarter.

33

Gross profit and gross margin

Gross profit improved $17.7 million and gross margin improved 360 basis points, largely the result of increased pricing outpacing higher costs and strong demand, as previously discussed. In addition, lower equipment operating costs, mainly fuel, had a positive impact on gross profit. Partially offsetting the increase was lower contracting services margins reducing gross profit by $2.4 million on lower revenues and cost overruns on a project in California.

EBITDA and EBITDA margin

EBITDA improved $11.3 million and EBITDA margin improved 210 basis points. These increases were the direct result of the previously discussed higher gross profit, partially offset by higher selling, general and administrative costs of $7.1 million. The increase in selling, general and administrative costs includes higher payroll-related costs of $3.9 million, due in part to higher incentive accruals based on the Company's performance; increased rent expense of $600,000; higher legal and other professional services of $600,000; higher insurance costs and building repair costs of $300,000 each; and increased other miscellaneous expenses.

Results of Operations - Northwest

	Three Months Ended							Nine Months Ended
	September 30,							September 30,
	2023			2022			% Change	2023			2022			% Change
	(In millions)
Revenue	$	209.4		$	204.7		2%	$	504.2		$	461.2		9%
Gross profit	$	50.6		$	44.1		15%	$	109.3		$	82.4		33%
Gross margin	24.1		%	21.5		%		21.7		%	17.9		%
EBITDA	$	48.9		$	43.8		12%	$	102.7		$	79.8		29%
EBITDA margin	23.3		%	21.4		%		20.4		%	17.3		%

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2023		2022		2023		2022
	(In millions)
Revenues:
Aggregates	$	57.4	$	52.6	$	147.9	$	129.7
Ready-mix concrete	46.7		45.6		125.3		121.1
Asphalt	43.5		45.1		84.9		79.8
Other*	4.5		4.5		11.5		11.8
Contracting services	93.5		99.1		218.9		202.1
Internal sales	(36.2)		(42.2)		(84.3)		(83.3)
	$	209.4	$	204.7	$	504.2	$	461.2

*Other includes merchandise, transportation services and other products that individually are not considered to be a core line of business for the segment.

Three Months Ended September 30, 2023, Compared to Three Months Ended September 30, 2022

Revenue

Revenue improved $4.7 million as a result of higher selling prices contributing an additional $17.2 million of revenue, which was driven by EDGE-related pricing initiatives across all product lines and increased sales of higher-priced aggregate products. Also contributing to higher revenues were increased asphalt sales volumes of $4.6 million in the north division, due in part to higher third-party sales. In addition, higher demand for contracting services of $5.8 million in the west division for Agency and railroad work and for prestress data center, manufacturing plant and infrastructure work positively impacted revenues. Partially offsetting these increases were decreased demand for asphalt paving work in the south and central divisions, which affected both asphalt product sales volumes and contracting services work by $21.4 million. Sales volumes for aggregates were also lower, largely due to project delays and lower overall demand in certain locations.

Gross profit and gross margin

Gross profit improved $6.5 million and gross margin improved 260 basis points. The increase was driven by higher sales prices outpacing costs on aggregate and asphalt products by $12.5 million, largely as a result of EDGE-related pricing initiatives and aggregates product mix. Partially offsetting the increase were the impacts of decreased sales volumes across all product lines, as previously discussed, and overall product mix.

34

EBITDA and EBITDA margin

EBITDA improved $5.1 million and EBITDA margin improved 190 basis points, directly resulting from the increased gross profit previously discussed. Partially offsetting the increase was higher selling, general and administrative expenses, including higher payroll-related costs of $1.1 million, loss on an asset disposal and higher other miscellaneous expenses.

Nine Months Ended September 30, 2023, Compared to Nine Months Ended September 30, 2022

Revenue

Revenue improved $43.0 million, largely the result of EDGE-related pricing initiatives on all product lines and increased sales of higher-priced aggregate products together contributing $44.4 million. In addition, higher demand for contracting services work related to Agency and railroad projects, as well as prestress data center and other projects, contributed to the increase. Partially offsetting the increases were lower sales volumes across all product lines of $16.9 million, due in part to the timing of impact projects in 2023, weather-related delays from earlier in the year and decreased demand for asphalt paving and residential work.

Gross profit and gross margin

Gross profit improved $26.9 million and gross margin improved 380 basis points. The increase was driven by higher sales prices outpacing costs across all product lines by $24.2 million, largely as a result of EDGE-related pricing initiatives and aggregates product mix, which was offset in part by decreased volumes across all product lines, as previously discussed. Contracting services gross profit improved by $4.5 million due to the strong backlog of work established and the reduction of job losses as compared to the prior year. In addition, lower per unit fuel costs had a positive impact on gross profit.

EBITDA and EBITDA margin

EBITDA improved $22.9 million and EBITDA margin improved 310 basis points, directly resulting from the increased gross profit previously discussed. Partially offsetting the increase was higher selling, general and administrative expenses of $6.1 million. The increase includes higher payroll-related costs of $3.0 million, primarily higher incentive accruals and wages; lower asset sale gains of $1.5 million; and higher other expenses, including office expenses, dues and subscriptions, professional services and property taxes.

Results of Operations - Mountain

	Three Months Ended							Nine Months Ended
	September 30,							September 30,
	2023			2022			% Change	2023			2022			% Change
	(In millions)
Revenue	$	255.1		$	204.1		25%	$	491.5		$	433.0		14%
Gross profit	$	60.7		$	40.9		48%	$	89.3		$	64.6		38%
Gross margin	23.8		%	20.0		%		18.2		%	14.9		%
EBITDA	$	60.4		$	39.6		53%	$	86.5		$	60.2		44%
EBITDA margin	23.7		%	19.4		%		17.6		%	13.9		%

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2023		2022		2023		2022
	(In millions)
Revenues:
Aggregates	$	39.5	$	31.3	$	78.1	$	67.4
Ready-mix concrete	44.1		37.3		93.0		85.0
Asphalt	59.7		45.6		89.9		77.0
Contracting services	179.6		139.0		339.0		294.3
Internal sales	(67.8)		(49.1)		(108.5)		(90.7)
	$	255.1	$	204.1	$	491.5	$	433.0

Three Months Ended September 30, 2023, Compared to Three Months Ended September 30, 2022

Revenue

Revenue improved $51.0 million, primarily the result of higher contracting services revenues from strong demand for commercial, residential, airport and Agency work, which also contributed to volume increases for asphalt and ready-mix concrete products. Pricing momentum across all product lines in response to rising costs, higher demand and growing markets contributed $21.7 million to the revenue increase. Aggregate sales volumes also increased $3.9 million, largely due to wind energy projects in Wyoming.

35

Gross profit and gross margin

Gross profit improved $19.8 million and gross margin improved 380 basis points. Higher margins on contracting services work due to higher revenues and higher bid margins contributed an additional $8.5 million in gross profit, while higher sales prices outpaced costs across all product lines by $8.4 million partly from EDGE-related initiatives, including operating efficiencies and pricing optimization. Lower overall equipment operating costs, largely related to fuel, also had a positive benefit in the quarter.

EBITDA and EBITDA margin

EBITDA improved $20.8 million and EBITDA margin improved 430 basis points, directly resulting from the increased gross profit previously discussed. Also positively impacting EBITDA was lower selling, general and administrative expenses, largely related to higher gains on asset sales.

Nine Months Ended September 30, 2023, Compared to Nine Months Ended September 30, 2022

Revenue

Revenue improved $58.5 million, primarily the result of increased contracting services revenues from strong demand for commercial, residential and Agency work throughout the region, offset partially by the absence in 2023 of an impact airport project substantially completed during the second quarter of 2022. Pricing momentum across all product lines of $34.1 million, in response to rising costs, demand and growing markets, also had a positive impact on revenues. In addition, aggregate volumes benefited by $4.8 million, largely due to increased demand in Montana and wind energy projects in Wyoming. Partially offsetting these increases were lower ready-mix concrete and asphalt volumes of $7.4 million, largely the result of unfavorable weather conditions in Wyoming.

Gross profit and gross margin

Gross profit improved $24.7 million and gross margin improved 330 basis points. The improvement was the result of higher contracting services margins contributing profit of $12.0 million due to strong markets for commercial, residential and Agency work throughout the region, as well as higher sales prices outpacing costs across all product lines by $10.7 million. Lower overall equipment operating costs, including fuel, also had a positive impact on the segment. Partially offsetting these increases was $1.4 million of higher depreciation expense.

EBITDA and EBITDA margin

EBITDA improved $26.3 million and EBITDA margin improved 370 basis points, directly resulting from the increased gross profit previously discussed.

36

Results of Operations - North Central

	Three Months Ended							Nine Months Ended
	September 30,							September 30,
	2023			2022			% Change	2023			2022			% Change
	(In millions)
Revenue	$	305.1		$	294.3		4%	$	513.7		$	484.4		6%
Gross profit	$	74.5		$	58.9		26%	$	82.8		$	55.7		49%
Gross margin	24.4		%	20.0		%		16.1		%	11.5		%
EBITDA	$	70.5		$	58.6		20%	$	71.4		$	50.4		42%
EBITDA margin	23.1		%	19.9		%		13.9		%	10.4		%

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2023		2022		2023		2022
	(In millions)
Revenues:
Aggregates	$	47.7	$	45.0	$	82.0	$	75.7
Ready-mix concrete	73.2		64.5		139.3		124.0
Asphalt	95.0		96.9		142.0		141.6
Other*	10.2		8.7		22.7		20.8
Contracting services	190.3		189.9		294.7		284.6
Internal sales	(111.3)		(110.7)		(167.0)		(162.3)
	$	305.1	$	294.3	$	513.7	$	484.4

*Other includes merchandise and other products that individually are not considered to be a core line of business for the segment.

Three Months Ended September 30, 2023, Compared to Three Months Ended September 30, 2022

Revenue

Revenue improved $10.8 million resulting from higher selling prices contributing an additional $30.1 million in revenue, largely due to pricing initiatives on all product lines, as well as product mix. Asphalt and aggregate sales volumes decreased $20.6 million, largely as the segment continues to target improved bid margins on smaller projects which also impacts internal sales volumes, as well as the absence of an impact project in South Dakota during 2022. Overall ready-mix concrete volumes were flat, with strong volumes in South Dakota from commercial and third-party sales being offset by decreased residential demand in Minnesota.

Gross profit and gross margin

Gross profit improved $15.6 million and gross margin improved 440 basis points. Higher contracting services margins contributed $10.3 million in gross profit, largely related to improved bid margins across the region and efficient execution of work leading to job productivity gains on a large concrete and asphalt paving job. Also, higher sales prices across all product lines outpaced cost increases by $7.2 million. Lower overall equipment operating costs, largely related to fuel, also had a positive benefit in the quarter of approximately $2.1 million. Partially offsetting these increases were lower aggregates and asphalt volumes, as previously discussed.

EBITDA and EBITDA margin

EBITDA improved $11.9 million and EBITDA margin improved 320 basis points, directly resulting from the increased gross profit previously discussed. Partially offsetting the increase was higher selling, general and administrative expenses of $3.7 million, largely higher payroll-related costs of $2.5 million, including higher wages and incentive and profit sharing accruals based on the Company's performance; decreased gains on asset sales of $500,000; and increased bad debt expense.

Nine Months Ended September 30, 2023, Compared to Nine Months Ended September 30, 2022

Revenue

Revenue improved $29.3 million as a result of higher selling prices across all product lines providing $51.8 million of additional revenue, largely due to EDGE-related pricing initiatives. Contracting services revenue saw a benefit of $10.1 million from improved bid margins across the region and a large concrete and asphalt paving job. Asphalt and aggregate sales volumes decreased $29.9 million, largely as the segment continues to target improved bid margins on projects which also impacts internal sales volumes, as well as the absence of an impact project in South Dakota. Overall ready-mix concrete volumes were flat, as strong volumes in South Dakota from commercial and paving projects and North Dakota from an impact project were mostly offset by softening residential demand in Minnesota.

37

Gross profit and gross margin

Gross profit improved $27.1 million and gross margin improved 460 basis points, largely due to higher contracting services margins of $14.0 million related to improved bid margins, impact projects and job productivity gains, as well as higher sales prices across all product lines outpacing cost increases by $11.6 million. Lower overall equipment operating costs, largely fuel, also had a positive benefit in the quarter of approximately $6.0 million. Partially offsetting these increases were lower aggregate and asphalt sales volumes, as previously discussed.

EBITDA and EBITDA margin

EBITDA improved $21.0 million and EBITDA margin improved 350 basis points, directly resulting from the increased gross profit previously discussed. Partially offsetting the increase was higher selling, general and administrative expenses of $6.3 million, primarily higher payroll-related costs of $4.7 million, including higher incentive and profit sharing accruals based on the Company's performance, as well as decreased gains on asset sales of $500,000; increased insurance costs of $300,000; and increased other miscellaneous expenses.

Results of Operations - All Other and Intersegment Eliminations

	Three Months Ended							Nine Months Ended
	September 30,							September 30,
	2023			2022			% Change	2023			2022			% Change
	(In millions)
Revenue	$	139.4		$	119.9		16%	$	282.7		$	252.5		12%
Gross profit	$	40.8		$	13.2		209%	$	73.4		$	32.2		128%
Gross margin	29.3		%	11.0		%		25.9		%	12.7		%
EBITDA	$	24.0		$	5.5		336%	$	35.3		$	5.6		533%
EBITDA margin	17.2		%	4.6		%		12.5		%	2.2		%

Three Months Ended September 30, 2023, Compared to Three Months Ended September 30, 2022

Revenue

Revenue improved $19.5 million, due largely to higher revenues from liquid asphalt. Timing of projects in certain markets, as well as market strength, drove liquid asphalt volumes up, while market pricing provided a benefit of $9.5 million for the quarter. In the South region, additional asphalt paving work and favorable weather in Texas contributed $6.1 million in revenue and higher selling prices across all product lines contributed $3.8 million. Additionally, the South region's Honey Creek quarry contributed additional aggregate volumes in the quarter as it became fully operational in the second quarter of 2023. Partially offsetting the increases were decreased ready-mix concrete and aggregates sales of $10.2 million due to a partial sale of non-strategic assets in southeast Texas in December 2022.

Gross profit and gross margin

Gross profit improved $27.6 million and gross margin improved 1,830 basis points, primarily due to higher liquid asphalt margins resulting from cost improvements and favorable sales price increases driven by market pricing, as well as the higher sales volumes previously mentioned. In addition, higher sales prices across all product lines in the South region contributed $2.9 million to gross profit, as previously discussed. Partially offsetting the increase in the South region was a decrease in aggregates and ready-mix concrete volumes, which resulted in a reduction to gross profit of $2.4 million, largely as a result of the partial sale of non-strategic assets in southeast Texas in December 2022.

EBITDA and EBITDA margin

EBITDA improved $18.5 million and EBITDA margin improved 1,260 basis points. The increase in EBITDA was the direct result of increased gross profit previously discussed, partially offset by higher selling, general and administrative costs of $9.8 million. As a result of the Separation from MDU Resources, the Company experienced increased payroll-related costs of $6.7 million, largely due to additional staff and stock-based compensation expense for the management team and board of directors, and higher professional services of $600,000, which were offset by a reduction in general corporate expenses from MDU Resources of $3.8 million, as discussed in Note 2. Also, as part of the Separation, the Company incurred one-time costs of $4.4 million, primarily related to professional services, insurance costs and the transition services agreement with MDU Resources, which was offset in part by income from the transition services agreement of $407,000. Further contributing to higher selling, general and administrative costs were increased payroll-related costs of $1.9 million due to higher incentive accruals based on the Company's performance.

38

Nine Months Ended September 30, 2023 Compared to Nine Months Ended September 30, 2022

Revenue

Revenue improved $30.2 million, largely driven by higher liquid asphalt revenue of $19.3 million because of market pricing, along with higher volumes from additional sales opportunities across most of its primary markets. The South region benefited from higher selling prices across all product lines, higher contracting services revenues of $8.6 million related to asphalt paving work and higher aggregate sales volumes as a result of the Honey Creek quarry operations. Partially offsetting these increases were decreased aggregate and ready-mix concrete sales of $22.8 million due to the partial sale of non-strategic assets in southeast Texas in December 2022.

Gross profit and gross margin

Gross profit improved $41.2 million and gross margin improved 1,320 basis points, primarily due to higher liquid asphalt margins resulting from favorable sales price increases driven by market pricing, cost improvements and higher sales volumes. The South region's gross profit increased $5.6 million from higher sales prices for asphalt and ready-mix concrete while contracting services margins increased as a result of improved bid margins. Partially offsetting the improvements was the impact of decreased ready-mix concrete volumes as a result of the partial sale of non-strategic assets in southeast Texas in December 2022.

EBITDA and EBITDA margin

EBITDA improved $29.7 million and EBITDA margin improved 1,030 basis points. The increase in EBITDA was the direct result of increased gross profit previously discussed, partially offset by higher selling, general and administrative costs of $17.7 million. As a result of the Separation from MDU Resources, the Company experienced increased recurring costs including payroll-related costs of $8.6 million, largely due to additional staff and stock-based compensation expense for the management team and board of directors; insurance costs of $1.5 million; and professional services of $900,000, which were offset in part by a reduction in general corporate expenses from MDU Resources of $4.7 million, as discussed in Note 2. Also, as part of the Separation, the Company incurred one-time costs of $7.1 million, primarily related to professional services, insurance costs and the transition services agreement with MDU Resources, which was offset in part by income from the transition services agreement of $684,000. Further contributing to higher selling, general and administrative costs were increased payroll-related costs due to higher incentive accruals based on the Company's performance.

Liquidity and Capital Resources

At September 30, 2023, Knife River had cash and cash equivalents of $84.0 million and working capital of $586.4 million. Working capital is calculated as current assets less current liabilities. Following the Separation, Knife River’s cash management, capital structure and liquidity sources have changed significantly. Knife River implemented its own centralized cash management model and intends to use cash on hand and third-party credit facilities to fund day-to-day operations. As of September 30, 2023, the Company believes it has sufficient liquid assets, cash flows from operations and borrowing capacity to meet its financial commitments, debt obligations and anticipated capital expenditures for at least the next 12 months.

Given the seasonality of its business, the Company typically experiences significant fluctuations in working capital needs and balances throughout the year. Working capital requirements generally increase in the first half of the year as the Company builds up inventory and focuses on preparing equipment and facilities and other start-up costs for its construction season. Working capital levels then decrease as the construction season winds down and the Company collects on receivables.

Knife River’s ability to fund its cash needs will depend on the ongoing ability to generate cash from operations and obtain debt financing with competitive rates. Knife River relies on access to capital markets as sources of liquidity for capital requirements not satisfied by cash flows from operations, particularly in the first half of the year due to the seasonal nature of the industry. Knife River’s principal uses of cash in the future will be to fund its operations, working capital needs, capital expenditures, repayment of debt and strategic business development transactions.

On April 25, 2023, Knife River issued $425.0 million of 7.75 percent senior notes due May 1, 2031. On May 31, 2023, Knife River entered into a senior secured credit agreement consisting of a $275.0 million term loan, with a balance outstanding of $273.3 million at September 30, 2023, and a $350.0 million revolving credit facility, with no outstanding borrowings at September 30, 2023. Each of the agreements under the senior secured credit agreement have a SOFR-based interest rate and a maturity date of May 31, 2028. For more information on the debt agreements and covenant restrictions, see Note 12.

Capital expenditures

Knife River currently estimates total 2023 capital expenditures to be $125.0 million, of which there is approximately $50.0 million remaining at September 30, 2023. These expenditures relate primarily to routine replacement and maintenance of vehicles and equipment, building improvements, aggregate reserves and storage facilities updates.

The Company continues to evaluate the potential for future acquisitions and other growth opportunities that would be incremental to the outlined capital program; however, these opportunities are dependent upon the availability of economic conditions. It is anticipated that all of the funds required for capital expenditures for 2023 will be funded by various sources, including internally generated funds and credit facilities.

39

Cash flows

	Nine Months Ended
	September 30,
	2023		2022
	(In millions)
Net cash provided by (used in)
Operating activities	$	152.9	$	39.4
Investing activities	(82.9)		(117.9)
Financing activities	36.1		83.7
Increase in cash, cash equivalents and restricted cash	106.1		5.2
Cash, cash equivalents and restricted cash -- beginning of year	10.1		13.8
Cash, cash equivalents and restricted cash -- end of period	$	116.2	$	19.0

Operating activities 

	Nine Months Ended
	September 30,
	2023		2022		Variance
	(In millions)
Components of net cash provided by operating activities:
Net income	$	162.2	$	98.2	$	64.0
Adjustments to reconcile net income to net cash provided by operating activities	93.0		95.0		(2.0)
Changes in current assets and liabilities, net of acquisitions:
Receivables	(302.5)		(239.6)		(62.9)
Due from related-party	16.1		1.3		14.8
Inventories	8.6		(18.6)		27.2
Other current assets	(20.2)		.8		(21.0)
Accounts payable	91.6		69.6		22.0
Due to related-party	(7.3)		9.8		(17.1)
Other current liabilities	78.0		21.8		56.2
Pension and postretirement benefit plan contributions	(1.6)		(.3)		(1.3)
Other noncurrent charges	35.0		1.4		33.6
Net cash provided by operating activities:	$	152.9	$	39.4	$	113.5

Cash provided by operating activities at September 30, 2023, increased $113.5 million, largely related to increased earnings in 2023 and lower working capital needs. Cash used by working capital components totaled $135.7 million for the nine months ended September 30, 2023, compared to $154.9 million for the nine months ended September 30, 2022. This reduction in cash usage was driven largely by the lower payments on operating expenses at the end of the period, higher accrued interest payments on long-term debt, and decreased liquid asphalt inventory balances, partially offset by increased accounts receivable balances associated with higher revenues during the quarter. In addition, the timing of insurance costs associated with the captive insurer had a positive impact on cash.

Investing activities

	Nine Months Ended
	September 30,
	2023		2022		Variance
	(In millions)
Capital expenditures	$	(86.4)	$	(121.8)	$	35.4
Acquisitions, net of cash acquired	—		.4		(.4)
Net proceeds from sale or disposition of property and other	5.2		5.7		(.5)
Investments	(1.7)		(2.2)		.5
Net cash used in investing activities	$	(82.9)	$	(117.9)	$	35.0

The decrease in cash used in investing activities for the nine months ended September 30, 2023, compared to the nine months ended September 30, 2022, was primarily due to a reduction in capital expenditures for the prestress facility in Washington that was completed during the third quarter of 2023.

40

Financing activities

	Nine Months Ended
	September 30,
	2023		2022		Variance
	(In millions)
Issuance of current related-party notes, net	$	—	$	100.0	$	(100.0)
Issuance of long-term related-party notes, net	205.3		26.9		178.4
Issuance of long-term debt	700.0		—		700.0
Repayment of long-term debt	(1.9)		(.2)		(1.7)
Debt issuance costs	(16.7)		(.7)		(16.0)
Net transfers to Centennial	(850.6)		(42.3)		(808.3)
Net cash provided by financing activities	$	36.1	$	83.7	$	(47.6)

The decrease in cash flows provided by financing activities for the nine months ended September 30, 2023, compared to the nine months ended September 30, 2022, was largely related to the changes in debt as a result of the Separation. For further information, see Note 18.

Material cash requirements

There were no material changes in the Company's contractual obligations from those reported in the Company's Registration Statement on Form 10 other than as set forth below. For more information on the Company's contractual obligations for related-party notes payable, operating leases and purchase commitments, see the Material Cash Requirements section in the Management's Discussion and Analysis of Financial Condition and Results of Operations section in the Company's Registration Statement on Form 10.

Material short-term and long-term cash requirements of the Company include repayment of third-party long-term debt and related interest payments, related-party notes payable and related interest payments, payments on operating lease agreements, payments of obligations on purchase commitments and asset retirement obligations.

At September 30, 2023, the Company's purchase commitments reflected an increase of approximately 36 percent from the balance at December 31, 2022. This increase is primarily from the Company committing to a three-year cement contract. Due to the seasonality of work and the third quarter being its peak construction season, the Company's purchase commitments saw an expected decrease from the balance at June 30, 2023. The Company expects purchase commitments to continue to decrease throughout the remainder of 2023 as obligations continue to be satisfied during the construction season.

At September 30, 2023, the Company's long-term debt reflected an increase of approximately $221.7 million from the balance at December 31, 2022. This increase is due to the Company paying off its short-term debt, and replacing it with long-term debt in preparation of the Separation.

At September 30, 2023, the Company's total estimated interest payments over the life of its debt reflected an increase of approximately $250.5 million from the total estimated interest payments at December 31, 2022. This increase is due to the rising interest rate environment in 2023 and higher rate debt incurred by the Company in preparation of the Separation. The Company's average interest rate has increased from 3.62% on December 31, 2022 to 6.90% on September 30, 2023. Estimated interest payments outstanding over the life of the loans was as follows:

	Remainder of 2023		1-3 years		3-5 years		More than 5 years		Total
	(In millions)
Estimated interest payments*	$	22.2	$	120.1	$	116.5	$	122.3	$	381.1

*Includes estimated interest payments of the Company's revolving credit facility assuming current interest rates and consistent amounts outstanding until its maturity date over the periods indicated above.

Defined benefit pension plans

The Company has noncontributory qualified defined benefit pension plans for certain employees. Various assumptions are used in calculating the benefit expense (income) and liability (asset) related to these plans, as such costs of providing these benefits bear the risk of changes as they are dependent upon assumptions of future conditions.

There were no other material changes to the Company's qualified noncontributory defined benefit pension plans from those reported in the Company's Registration Statement on Form 10 other than the Company contributed approximately $1.2 million to its pension plans during the third quarter. The contribution was largely as a result of the decline in asset values in 2022 decreasing the funded status of the plans. For more information, see Note 17 of the Audited Annual Consolidated Financial Statements in the Company's Registration Statement on Form 10.

41

Non-GAAP Financial Measures

The Business Segment Financial and Operating Data includes financial information prepared in accordance with GAAP, as well as EBITDA, EBITDA margin, Adjusted EBITDA and Adjusted EBITDA Margin financial measures. Knife River defines EBITDA as net income before interest expense, taxes and depreciation, depletion and amortization, and EBITDA margin as EBITDA as a percentage of revenues. Knife River defines Adjusted EBITDA as EBITDA, further adjusted to exclude unrealized gains and losses on benefit plan investments, stock-based compensation and one-time Separation costs, and Adjusted EBITDA Margin as Adjusted EBITDA as a percentage of revenues.

EBITDA, EBITDA margin, Adjusted EBITDA and Adjusted EBITDA Margin, including those measures by segment, are considered non-GAAP financial measures and are most directly comparable to the corresponding GAAP measures of net income, net income margin, gross profit and gross margin. Knife River believes these non-GAAP financial measures, in addition to corresponding GAAP measures, are useful to investors by providing meaningful information about operational efficiency compared to its peers by excluding the impacts of differences in tax jurisdictions and structures, debt levels and capital investment. Management believes Adjusted EBITDA is a useful performance measure because it allows for an effective evaluation of the Company's operating performance by excluding stock-based compensation and unrealized gains and losses on benefit plan investments as they are considered non-cash and not part of the Company's core operations. The Company also excludes the one-time, non-recurring costs associated with the Separation as those are not expected to continue. Rating agencies and investors also use EBITDA and Adjusted EBITDA to calculate Knife River’s leverage as a multiple of EBITDA and Adjusted EBITDA. Additionally, EBITDA and Adjusted EBITDA are important financial metrics for debt investors who utilize debt to EBITDA and debt to Adjusted EBITDA ratios. Knife River's management believes EBITDA and EBITDA margin, including those measures by segment, are useful performance measures because they provide clarity as to the operational results of the Company. Knife River’s management uses these non-GAAP financial measures in conjunction with GAAP results when evaluating its operating results internally and calculating employee incentive compensation, and leverage as a multiple of EBITDA and Adjusted EBITDA to determine the appropriate method of funding operations of the Company.

EBITDA is calculated by adding back income taxes, interest expense and depreciation, depletion and amortization expense to net income. EBITDA margin is calculated by dividing EBITDA by revenues. Adjusted EBITDA is calculated by adding back unrealized gains and losses on benefit plan investments, stock-based compensation and one-time Separation costs, to EBITDA. Adjusted EBITDA margin is calculated by dividing Adjusted EBITDA by revenues. These non-GAAP financial measures are calculated the same by segment and consolidated and should not be considered as alternatives to, or more meaningful than, GAAP financial measures such as net income or net income margin and are intended to be helpful supplemental financial measures for investors’ understanding of Knife River’s operating performance. Knife River’s non-GAAP financial measures are not standardized; therefore, it may not be possible to compare these financial measures with other companies’ EBITDA, EBITDA margin, Adjusted EBITDA and Adjusted EBITDA Margin measures having the same or similar names.

The following information reconciles consolidated and segment net income to EBITDA and EBITDA to Adjusted EBITDA and provides the calculation of EBITDA margin and adjusted EBITDA margin. Interest expense, net, is net of interest income that is included in other income on the Consolidated Statements of Operations.

Three Months Ended September 30, 2023	Pacific			Northwest			Mountain			North Central			All Other and Intersegment Eliminations			Consolidated
	(In millions)
Net income (loss)	$	31.9		$	39.1		$	54.1		$	64.4		$	(42.8)		$	146.7
Depreciation, depletion and amortization	5.7			9.8			6.3			6.1			3.9			31.8
Interest expense, net	—			—			—			—			14.7			14.7
Income taxes	—			—			—			—			48.2			48.2
EBITDA	$	37.6		$	48.9		$	60.4		$	70.5		$	24.0		$	241.4
Unrealized (gains) losses on benefit plan investments													.6			.6
Stock-based compensation expense													1.5			1.5
One-time separation costs													4.0			4.0
Adjusted EBITDA													$	30.1		$	247.5
Revenue	$	181.4		$	209.4		$	255.1		$	305.1		$	139.4		$	1,090.4
Net income margin	17.6		%	18.7		%	21.2		%	21.1		%	(30.7)		%	13.4		%
EBITDA margin	20.7		%	23.3		%	23.7		%	23.1		%	17.2		%	22.1		%
Adjusted EBITDA margin													21.6		%	22.7		%

42

Three Months Ended September 30, 2022	Pacific			Northwest			Mountain			North Central			All Other and Intersegment Eliminations			Consolidated
	(In millions)
Net income (loss)	$	19.0		$	34.6		$	33.8		$	52.5		$	(40.2)		$	99.7
Depreciation, depletion and amortization	5.6			9.2			5.8			6.1			3.8			30.5
Interest expense, net	—			—			—			—			8.8			8.8
Income taxes	—			—			—			—			33.1			33.1
EBITDA	$	24.6		$	43.8		$	39.6		$	58.6		$	5.5		$	172.1
Unrealized (gains) losses on benefit plan investments													.8			.8
Stock-based compensation expense													.2			.2
Adjusted EBITDA													$	6.5		$	173.1
Revenue	$	152.4		$	204.7		$	204.1		$	294.3		$	119.9		$	975.4
Net income margin	12.5		%	16.9		%	16.6		%	17.8		%	(33.5)		%	10.2		%
EBITDA margin	16.1		%	21.4		%	19.4		%	19.9		%	4.6		%	17.6		%
Adjusted EBITDA margin													5.5		%	17.8		%

Nine Months Ended September 30, 2023	Pacific			Northwest			Mountain			North Central			All Other and Intersegment Eliminations			Consolidated
	(In millions)
Net income (loss)	$	39.8		$	74.3		$	67.9		$	53.5		$	(73.3)		$	162.2
Depreciation, depletion and amortization	16.7			28.4			18.5			17.9			11.0			92.5
Interest expense, net	—			—			.1			—			41.3			41.4
Income taxes	—			—			—			—			56.3			56.3
EBITDA	$	56.5		$	102.7		$	86.5		$	71.4		$	35.3		$	352.4
Unrealized (gains) losses on benefit plan investments													(1.1)			(1.1)
Stock-based compensation expense													2.3			2.3
One-time separation costs													6.4			6.4
Adjusted EBITDA													$	42.9		$	360.0
Revenue	$	391.4		$	504.2		$	491.5		$	513.7		$	282.7		$	2,183.5
Net income margin	10.2		%	14.7		%	13.8		%	10.4		%	(25.9)		%	7.4		%
EBITDA margin	14.4		%	20.4		%	17.6		%	13.9		%	12.5		%	16.1		%
Adjusted EBITDA margin													15.2		%	16.5		%

43

Nine Months Ended September 30, 2022	Pacific			Northwest			Mountain			North Central			All Other and Intersegment Eliminations			Consolidated
	(In millions)
Net income (loss)	$	29.1		$	53.4		$	43.0		$	32.5		$	(59.8)		$	98.2
Depreciation, depletion and amortization	16.1			26.4			17.1			17.9			11.1			88.6
Interest expense, net	—			—			.1			—			21.4			21.5
Income taxes	—			—			—			—			32.9			32.9
EBITDA	$	45.2		$	79.8		$	60.2		$	50.4		$	5.6		$	241.2
Unrealized (gains) losses on benefit plan investments													4.8			4.8
Stock-based compensation expense													1.6			1.6
Adjusted EBITDA													$	12.0		$	247.6
Revenue	$	366.1		$	461.2		$	433.0		$	484.4		$	252.5		$	1,997.2
Net income margin	8.0		%	11.6		%	9.9		%	6.7		%	(23.7)		%	4.9		%
EBITDA margin	12.3		%	17.3		%	13.9		%	10.4		%	2.2		%	12.1		%
Adjusted EBITDA margin													4.7		%	12.4		%

New Accounting Standards

For information regarding new accounting standards, see Note 2, which is incorporated by reference.

Critical Accounting Estimates

Knife River's critical accounting estimates include impairment testing of goodwill; fair values of acquired assets and liabilities under the acquisition method of accounting; revenue recognized using the cost-to-cost measure of progress for contracts; actuarially determined benefit costs; and tax provisions. There were no material changes in the Company's critical accounting estimates from those that were previously reported in the Company's Registration Statement on Form 10.

Item 3. Quantitative and Qualitative Disclosures About Market Risk

The Company is exposed to the impact of market fluctuations associated with interest rates and commodity prices. The Company has policies and procedures to assist in controlling these market risks and from time to time has utilized derivatives to manage a portion of its risk.

Interest rate risk

Rising interest rates have resulted in, and will likely continue to result in, higher borrowing costs on new debt and existing variable interest rate debt. Knife River entered into a senior secured credit agreement with variable rate debt arrangements at the time of the Separation, which could impact the interest expense recognized in future periods. For additional information on the debt agreements the Company has entered into, see the section entitled "Liquidity and Capital Resources". At September 30, 2023, the Company had $273.3 million in term loan borrowings under the credit agreement at the rate in effect at this time of 7.52%. A hypothetical increase of 1 percent on the interest rate of the term loan borrowings would increase interest expense by $2.7 million over the next 12 months.

At September 30, 2023, the Company had no outstanding interest rate hedges.

Commodity price risk

There were no material changes to commodity price risk faced by the Company from those reported in the Company's Registration Statement on Form 10.

Item 4. Controls and Procedures

Evaluation of disclosure controls and procedures

The term "disclosure controls and procedures" is defined in Rules 13a-15(e) and 15d-15(e) under the Exchange Act. The Company's disclosure controls and other procedures are designed to provide reasonable assurance that information required to be disclosed in the reports that the Company files or submits under the Exchange Act is recorded, processed, summarized and reported within the time periods specified in the SEC's rules and forms. The Company's disclosure controls and other procedures are designed to provide reasonable assurance that information required to be disclosed is accumulated and communicated to management, including the Company's chief executive officer and chief financial officer, to allow timely decisions regarding required disclosure. The Company's management, with the participation of the Company's chief executive officer and chief financial officer, has evaluated the effectiveness of the Company's disclosure controls and other procedures as of the end of the period

44

covered by this report. Based upon that evaluation, the chief executive officer and the chief financial officer have concluded that, as of the end of the period covered by this report, such controls and procedures were effective at a reasonable assurance level.

Changes in internal controls

No change in the Company's internal control over financial reporting (as defined in Rules 13a-15(f) and 15d-15(f) under the Exchange Act) occurred during the three months ended September 30, 2023, that has materially affected, or is reasonably likely to materially affect, the Company's internal control over financial reporting.

45

Part II -- Other Information

Item 1. Legal Proceedings

There were no material changes to the Company's legal proceedings that were previously reported in the Company's Registration Statement on Form 10.

Item 1A. Risk Factors

Refer to the Company's risk factors that are disclosed within its Registration Statement on Form 10 that could be materially harmful to the Company's business, prospects, financial condition or financial results if they occur. At September 30, 2023, there were no material changes to the Company's risk factors provided in the Company's Form 10.

Item 2. Unregistered Sales of Equity Securities, Use of Proceeds, and Issuer Purchases of Equity Securities

None.

Item 3. Defaults Upon Senior Securities

None.

Item 4. Mine Safety Disclosures

For information regarding mine safety violations or other regulatory matters required by Section 1503(a) of the Dodd-Frank Act and Item 104 of Regulation S-K, see Exhibit 95 to this Form 10-Q, which is incorporated herein by reference.

Item 5. Other Information

During the three months ended September 30, 2023, no director or officer of the Company adopted or terminated a “Rule 10b5-1 trading arrangement” or “non-Rule 10b5-1 trading arrangement,” as each term is defined in Item 408(a) of Regulation S-K.

Item 6. Exhibits

See the index to exhibits immediately preceding the signature page to this report.

46

Exhibits Index
			Incorporated by Reference
Exhibit Number	Exhibit Description	Filed Herewith	Form	Period Ended	Exhibit	Filing Date	File Number
3(a)	Amended and Restated Certificate of Incorporation of Knife River Corporation		8-K		3.1	6/01/23	1-41642
3(b)	Amended and Restated Bylaws of Knife River Corporation		8-K		3.2	6/01/23	1-41642
+10(a)	Restricted Stock Unit Award Agreement under the Long-Term Performance-Based Incentive Plan, effective July 12, 2023	X
31(a)	Certification of Chief Executive Officer filed pursuant to Section 302 of the Sarbanes-Oxley Act of 2002	X
31(b)	Certification of Chief Financial Officer filed pursuant to Section 302 of the Sarbanes-Oxley Act of 2002	X
32	Certification of Chief Executive Officer and Chief Financial Officer furnished pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002	X
95	Mine Safety Disclosures	X
101.INS	XBRL Instance Document - the instance document does not appear in the Interactive Data File because its XBRL tags are embedded within the Inline XBRL document
101.SCH	XBRL Taxonomy Extension Schema Document
101.CAL	XBRL Taxonomy Extension Calculation Linkbase Document
101.DEF	XBRL Taxonomy Extension Definition Linkbase Document
101.LAB	XBRL Taxonomy Extension Label Linkbase Document
101.PRE	XBRL Taxonomy Extension Presentation Linkbase Document
104	Cover Page Interactive Data File (formatted as Inline XBRL and contained in Exhibit 101)
+ Management contract, compensatory plan or arrangement.

47

Signatures

Pursuant to the requirements of the Exchange Act, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

		Knife River Corporation
DATE:	November 6, 2023	BY:	/s/ Nathan W. Ring
			Nathan W. Ring
			Vice President and Chief Financial Officer
		BY:	/s/ Marney L. Kadrmas
			Marney L. Kadrmas
			Chief Accounting Officer

48

EX-10.A

KNIFE RIVER CORPORATION

RESTRICTED STOCK UNIT AWARD NOTICE

This Award Notice evidences the award of restricted stock units (each, an “RSU” or collectively, the “RSUs”) that have been granted to, (xxxxxxxxxxxxxx), by Knife River Corporation, a Delaware corporation (the “Company”), subject to your acceptance of the terms of this Award Notice, the Restricted Stock Unit Award Agreement, which is attached hereto (the “Agreement”) and the Knife River Corporation Long-Term Performance-Based Incentive Plan (the “Plan”). When vested, each RSU entitles you to receive one share of common stock of the Company (the “Shares”). The RSUs are granted pursuant to the terms of the Plan.

This Award Notice constitutes part of, and is subject to the terms and provisions of, the Agreement and the Plan, which are incorporated by reference herein. Capitalized terms used but not defined in this Award Notice shall have the meanings set forth in the Agreement or in the Plan.

Grant Date:	July 12, 2023
Number of RSUs:	xxxxxx, subject to adjustment as provided under Section
	4.2 of the Plan.
Vesting Schedule:	Subject to the provisions of the Agreement and the Plan and provided that you remain continuously employed by the Company and/or an Affiliate through the respective vesting dates set forth below, the RSUs shall vest on December 31, 2025. The Vesting Schedule is the 36 month period beginning January 1, 2023 and ending December 31, 2025. Except for termination of employment due to retirement after the Participant has reached age 55 and completed 10 Years of Service, death or disability or a Change of Control as defined in the Plan, any unvested portion of the Award will be forfeited and/or cancelled on the date you cease to be an employee of the Company or an Affiliate.
Settlement Date:	Each vested RSU will be settled in Shares as soon as practicable following vesting but in no event later than 60 days after such RSUs vest.
Acceleration on Retirement, Death or Disability:	In the case of death or disability, a portion of the unvested RSUs will vest based on the ratio of the number of full months of employment completed during the Vesting Schedule to the date of your death or disability divided by the total number of months in the Vesting Schedule. In the case of retirement where the Participant has reached age 55 and completed 10 Years of Service (i) during the first year of the Vesting Schedule, all RSUs (and related Dividend Equivalents) shall be forfeited; (ii) during the second year of the Vesting Schedule, determination of the vesting RSUs will be made by the Committee at the end of the Vesting Schedule, and Shares (and related Dividend Equivalents) earned, if any, will be paid based on a proration for the number of months employed during the 36 month Vesting Schedule, including the month in which the

termination of employment occurs; and (iii) during the third year of the Vesting Schedule, determination of the vesting RSUs will be made by the Committee at the end of the Vesting Schedule, and Shares (and related Dividend Equivalents) earned, if any, will be paid without prorating. For purposes of the Award Agreement, the term Years of Service shall mean the full 12 month years a Participant is employed by the Company and/or a Subsidiary.

Dividend Equivalents:

Yes

THESE RESTRICTED STOCK UNITS ARE SUBJECT TO FORFEITURE AS PROVIDED HEREIN. THIS AWARD AND AMOUNTS RECEIVED IN CONNECTION WITH THIS AWARD ARE SUBJECT TO FORFEITURE, RECAPTURE OR OTHER ACTION IN THE EVENT OF AN ACCOUNTING RESTATEMENT, AS PROVIDED IN THE PLAN.

Further terms and conditions of the Award are set forth in Annex A hereto, which is an integral part of the Agreement.

You must accept this Award Notice by logging onto your account with Fidelity Investments and accepting this Award Notice and the Agreement. If you fail to do so, the RSUs will be null and void. By accepting the RSUs granted to you in this Award, you agree to be bound by all of the provisions set forth in this Award Notice, the Agreement, and the Plan.

Attachments:

Annex A: Restricted Stock Unit Award Agreement

Annex A

RESTRICTED STOCK UNIT AWARD AGREEMENT UNDER THE KNIFE RIVER CORPORATION

LONG-TERM PERFORMANCE-BASED INCENTIVE PLAN

Knife River Corporation (the “Company”) has granted to you an Award consisting of restricted stock units, subject to the terms and conditions set forth herein and in the Restricted Stock Unit Award Notice (the “Award Notice”). The Award has been granted to you pursuant to the Knife River Corporation Long-Term Performance-Based Incentive Plan (the “Plan”). Subject to the terms of the Plan, decisions and interpretations of the Compensation Committee of the Company’s Board of Directors (the “Committee”) are binding, conclusive and final upon any questions arising under the Award Notice, this Restricted Stock Unit Award Agreement (the “Agreement”) or the Plan. Unless otherwise defined herein or in the Award Notice, capitalized terms shall have the meanings assigned to such terms in the Plan.

1.Grant of RSUs. On the Grant Date, you were awarded the number of RSUs set forth in the Award Notice.

2.Vesting of RSUs. The RSUs shall become vested and nonforfeitable in accordance with the Vesting Schedule set forth in the Award Notice. Vesting may be accelerated only as described in the Award Notice.

3.Termination of employment. Except for termination of employment due to death, disability, retirement upon reaching age 55 with 10 Years of Service, or a Change of Control as defined in the Plan, any unvested portion of the Award will be forfeited and/or cancelled on the date you cease to be an employee of the Company or an Affiliate.

4.Settlement of RSU. Each RSU, at the discretion of the Committee, will be settled in Shares as soon as practicable after the Vesting Date but in no event later than 60 days after unvested RSUs become vested RSUs. You shall retain 50% of the net after-tax Shares that are earned under this Award until the earlier of (i) the end of the two-year period commencing on the date any Shares earned under this Award are issued and (ii) your termination of employment. Executives are required to own Shares at designated multiples of their base salary. If you have not achieved an applicable stock ownership requirement, the Company may require you to hold additional net after-tax Shares received under this Award until the requirement is met.

5.Voting Rights. Since RSUs do not represent actual Shares, no voting rights or other rights as a stockholder of the Company arise with respect to the RSUs until Shares have been delivered to you upon settlement of the RSUs.

6.Dividend Equivalents. Dividend Equivalents will be earned with respect to any Shares issued pursuant to the Award. The amount of Dividend Equivalents earned shall be equal to the total dividends declared on a Share for stockholders of record between the Grant Date of this Award and the vesting date of the RSUs, multiplied by the number of Shares issued pursuant to the vesting of the RSUs awarded in the Award Agreement. Any Dividend Equivalents earned shall be paid in cash when the Shares to which they relate are issued or as soon thereafter as practicable, but no later than 60 days after the Shares are issued. No Dividend Equivalents will be issued for unvested or forfeited RSUs.

7.Tax Withholding. Pursuant to Article 14 of the Plan, the Committee has the power and the right to deduct or withhold, or require the Participant to remit to the Company, an amount sufficient to satisfy any federal, state and local taxes (including the Participant's FICA obligations) required by law to be withheld with respect to the Award and Dividend Equivalents. The Committee may condition the delivery of vested Shares upon the Participant's

satisfaction of such withholding obligations. The withholding requirement for Shares will be satisfied by the Company withholding Shares having a Fair Market Value equal to federal income tax withholding obligations using an IRS accepted methodology plus additional amounts for state and local tax purposes, as applicable, including payroll taxes, that are applicable to such supplemental taxable income but with rates not to exceed the maximum effective statutory rates, unless the Participant elects, in a manner satisfactory to the Committee, to remit an amount to satisfy the withholding requirement subject to such restrictions or limitations that the Committee, in its sole discretion, deems appropriate. Such election must be made before, and is irrevocable after, December 15 of the last year in the Vesting Schedule, and cannot be made or revoked while the Participant possesses information that will be material nonpublic information at the time the Shares are issued such that the Participant would be prohibited from trading on the Company’s stock under its Insider Trading Policy.

8.Non-Guarantee of Employment Relationship or Future Awards. Nothing in the Plan, the Award Notice or this Agreement will alter your at-will or other employment status with the Company or an Affiliate, nor be construed as a contract of employment between you and the Company or an Affiliate, or as a contractual right for you to continue in the employ of the Company or an Affiliate for any period of time, or as a limitation of the right of the Company or an Affiliate to discharge you at any time with or without cause or notice and whether or not such discharge results in the forfeiture of any of your RSUs, or as a right to any future Awards.

9.Non-transferability of RSUs. No RSUs granted under the Plan may be sold, transferred, pledged, assigned, or otherwise alienated or hypothecated, other than by will or by the laws of descent and distribution.

10.Personal Information. You agree the Company and its suppliers or vendors may collect, use and disclose your personal information for the purposes of the implementation, management, administration and termination of the Plan.

11.Amendment. The Committee may amend, alter, modify, suspend or terminate the Award Notice or this Agreement at any time and from time to time, in whole or in part; provided, however, no amendment, alteration, modification, suspension or termination of the Award Notice or Agreement shall adversely affect in any material way the Award Notice or this Agreement, without your written consent, except to the extent such amendment, alteration, modification, suspension or termination is reasonably determined by the Committee in its sole discretion to be necessary to comply with applicable laws, rules, regulations, or is necessary for such approvals by any governmental agencies or national securities exchanges as may be required.

12.Binding Effect. This Agreement shall inure to the benefit of the successors and assigns of the Company and, subject to the restrictions on transfer set forth herein, be binding upon you and your heirs, beneficiaries, executors, legal representatives, successors and assigns.

13.Integrated Agreement. The Award Notice, this Agreement and the Plan constitute the entire understanding and agreement between you and the Company with respect to the subject matter contained herein or therein and supersedes any prior agreements, understandings, restrictions, representations, or warranties between you and the Company with respect to such subject matter other than those as set forth or provided for herein or therein.

14.Ratification of Actions. By accepting the Award or other benefit under the Plan, you and each person claiming under or through you shall be conclusively deemed to have indicated your acceptance and ratification of, and consent to, any action taken under the Plan or the Award by the Company, its Board of Directors, or the Committee.

15.Notices. Any notice hereunder to the Company shall be addressed to its office, 1150 West Century Avenue, Bismarck, North Dakota 58503; Attention: Corporate Secretary, and any notice hereunder to you shall be addressed to you at the address specified on the Award Agreement, subject to the right of either party to designate at any time hereafter in writing some other address.

16.Governing Law. To the extent not preempted by Federal law, the Award Notice and this Agreement shall be governed and construed in accordance with the laws of the State of Delaware, without regard to conflicts of law provisions. In the event any provision of the Award Agreement shall be held illegal or invalid for any reason, the illegality or invalidity shall not affect the remaining parts of the Award Agreement, and the Award Agreement shall be construed and enforced as if the illegal or invalid provision had not been included.

17.Construction. Captions and titles contained in this Agreement are for convenience only and shall not affect the meaning or interpretation of any provision of this Agreement. Except when otherwise indicated by the context, the singular shall include the plural and the plural shall include the singular. Use of the term “or” is not intended to be exclusive, unless the context clearly requires otherwise.

18.Conformity. This Agreement is intended to conform in all respects with, and is subject to all applicable provisions of, the Plan. Any conflict between the terms of the Award Notice, this Agreement and the Plan shall be resolved in accordance with the terms of the Plan. In the event of any ambiguity in the Award Notice or this Agreement or any matters as to which the Award Notice and this Agreement are silent, the Plan shall govern. Any conflict between the terms of the Award Notice and the Agreement shall be resolved in accordance with the terms of the Agreement.

EX-31.A

CERTIFICATION

I, Brian R. Gray, certify that:

1.I have reviewed this quarterly report on Form 10-Q of Knife River Corporation;

2.Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3.Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4.The registrant's other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e))and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

(a)Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

(b)Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

(c)Evaluated the effectiveness of the registrant's disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

(d)Disclosed in this report any change in the registrant's internal control over financial reporting that occurred during the registrant's most recent fiscal quarter (the registrant's fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant's internal control over financial reporting; and

5.The registrant's other certifying officer and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant's auditors and the audit committee of the registrant's board of directors (or persons performing the equivalent functions):

(a)All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant's ability to record, process, summarize and report financial information; and

(b)Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant's internal control over financial reporting.

Date: November 6, 2023 

/s/ Brian R. Gray

Brian R. Gray

President and Chief Executive Officer

EX-31.B

CERTIFICATION

I, Nathan W. Ring, certify that:

1.I have reviewed this quarterly report on Form 10-Q of Knife River Corporation;

2.Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3.Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4.The registrant's other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e))and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

(a)Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

(b)Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

(c)Evaluated the effectiveness of the registrant's disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

(d)Disclosed in this report any change in the registrant's internal control over financial reporting that occurred during the registrant's most recent fiscal quarter (the registrant's fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant's internal control over financial reporting; and

5.The registrant's other certifying officer and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant's auditors and the audit committee of the registrant's board of directors (or persons performing the equivalent functions):

(a)All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant's ability to record, process, summarize and report financial information; and

(b)Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant's internal control over financial reporting.

Date:  November 6, 2023

/s/ Nathan W. Ring

Nathan W. Ring

Vice President and Chief Financial Officer

EX-32

CERTIFICATION PURSUANT TO 18 U.S.C. SECTION 1350,

AS ADOPTED PURSUANT TO SECTION 906

OF THE SARBANES-OXLEY ACT OF 2002

    Each of the undersigned, Brian R. Gray, the President and Chief Executive Officer, and Nathan W. Ring, the Vice President and Chief Financial Officer of Knife River Corporation (the "Company"), DOES HEREBY CERTIFY that:

    1.  The Company's Quarterly Report on Form 10-Q for the quarter ended September 30, 2023 (the "Report"), fully complies with the requirements of Section 13(a) of the Securities Exchange Act of 1934; and

    2.  Information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company.

    IN WITNESS WHERE OF, each of the undersigned has executed this statement this 6th day of November, 2023.

/s/ Brian R. Gray

Brian R. Gray

President and Chief Executive Officer

/s/ Nathan W. Ring

Nathan W. Ring

Vice President and Chief Financial Officer

A signed original of this written statement required by Section 906 has been provided to Knife River Corporation and will be retained by Knife River Corporation and furnished to the Securities and Exchange Commission or its staff upon request.

EX-95

MDU RESOURCES GROUP, INC.

MINE SAFETY INFORMATION

The Dodd-Frank Wall Street Reform and Consumer Protection Act (Dodd-Frank Act) requires issuers to include in periodic reports filed with the SEC certain information relating to citations or orders for violations of standards under the Federal Mine Safety and Health Act of 1977 (Mine Act), as amended by the Mine Improvement and New Emergency Response Act of 2006 (Mine Safety Act). The Dodd-Frank Act requires reporting of the following types of citations or orders:

1.    Citations issued under Section 104 of the Mine Safety Act for violations that could significantly and substantially contribute to the cause and effect of a coal or other mine safety or health hazard.

2.    Orders issued under Section 104(b) of the Mine Safety Act. Orders are issued under this section when citations issued under Section 104 have not been totally abated within the time period allowed by the citation or subsequent extensions.

3.    Citations or orders issued under Section 104(d) of the Mine Safety Act. Citations or orders are issued under this section when it has been determined that the violation is caused by an unwarrantable failure of the mine operator to comply with the standards. An unwarrantable failure occurs when the mine operator is deemed to have engaged in aggravated conduct constituting more than ordinary negligence.

4.    Citations issued under Section 110(b)(2) of the Mine Safety Act for flagrant violations. Violations are considered flagrant for repeat or reckless failures to make reasonable efforts to eliminate a known violation of a mandatory health and safety standard that substantially and proximately caused, or reasonably could have been expected to cause, death or serious bodily injury.

5.    Imminent danger orders issued under Section 107(a) of the Mine Safety Act. An imminent danger is defined as the existence of any condition or practice in a coal or other mine which could reasonably be expected to cause death or serious physical harm before such condition or practice can be abated.

6.    Notice received under Section 104(e) of the Mine Safety Act of a pattern of violations or the potential to have such a pattern of violations that could significantly and substantially contribute to the cause and effect of mine health and safety standards.

During the three months ended September 30, 2023, none of the Company's operating subsidiaries received citations or orders under the following sections of the Mine Safety Act: 104(b), 104(d), 110(b)(2), 107(a) or 104(e). The Company did not have any mining-related fatalities during this period.

MSHA Identification Number/Contractor ID	Section 104 S&S Citations (#)	Total Dollar Value of MSHA Assessments Proposed ($)		Legal Actions Resolved During Period (#)
04-05140	—	286		—
21-03348	—	143		—
24-00462	1	—		—
32-00776	—	1,001		—
35-00521	—	429		—
35-03751	—	286		—
39-01478	—	429		—
41-02639	—	143		—
41-05498	—	429		—
50-00883	1	—		—
51-00036	—	975		—
39-00008	1	—
48-01518	—	—		4
48-01598	—	286
	3	$	4,407	4

Legal actions pending before the Federal Mine Safety and Health Review Commission (the Commission) may involve, among other questions, challenges by operators to citations, orders and penalties they have received from the Federal Mine Safety and Health Administration (MSHA) or complaints of discrimination by miners under section 105 of the Mine Act. The following is a brief description of the types of legal actions that may be brought before the Commission.

1

•Contests of Citations and Orders - A contest proceeding may be filed with the Commission by operators, miners or miners' representatives to challenge the issuance of a citation or order issued by MSHA.

•Contests of Proposed Penalties (Petitions for Assessment of Penalties) - A contest of a proposed penalty is an administrative proceeding before the Commission challenging a civil penalty that MSHA has proposed for the alleged violation contained in a citation or order.

•Complaints for Compensation - A complaint for compensation may be filed with the Commission by miners entitled to compensation when a mine is closed by certain withdrawal orders issued by MSHA. The purpose of the proceeding is to determine the amount of compensation, if any, due miners idled by the orders.

•Complaints of Discharge, Discrimination or Interference - A discrimination proceeding is a case that involves a miner's allegation that he or she has suffered a wrong by the operator because he or she engaged in some type of activity protected under the Mine Act, such as making a safety complaint.

•Applications for Temporary Relief - Applications for temporary relief from any modification or termination of any order or from any order issued under section 104 of the Mine Act.

•Appeals of Judges' Decisions or Orders to the Commission - A filing with the Commission for discretionary review of a judge's decision or order by a person who has been adversely affected or aggrieved by such decision or order.

The following table reflects the types of legal actions pending before the Commission as of September 30, 2023:

MSHA Identification Number	Contests of Citations and Orders	Contests of Proposed Penalties	Complaints for Compensation	Complaints of Discharge, Discrimination or Interference	Applications for Temporary Relief	Appeals of Judges' Decisions or Orders to the Commission
	—	—	—	—	—	—

2

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Cover page - shares	9 Months Ended
	Sep. 30, 2023	Nov. 01, 2023
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2023
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	No
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		56,566,214
Entity Central Index Key	0001955520
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q3
Amendment Flag	false

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Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Revenue:
Revenues	$ 1,090,372	$ 975,428	$ 2,183,462	$ 1,997,207
Cost of revenue:
Cost of Revenue	820,983	790,941	1,756,994	1,708,265
Gross profit	269,389	184,487	426,468	288,942
Selling, general and administrative expenses	59,168	41,572	167,276	130,223
Operating income	210,221	142,915	259,192	158,719
Interest expense	15,354	8,817	44,005	21,506
Other income (expense)	7	(1,277)	3,311	(6,056)
Income before income taxes	194,874	132,821	218,498	131,157
Income tax expense	48,219	33,164	56,327	32,947
Net income	$ 146,655	$ 99,657	$ 162,171	$ 98,210
Net income (loss) per share, basic
Income per share, Basic, Total	$ 2.59	$ 1.76	$ 2.87	$ 1.74
Net income (loss) per share, diluted
Income per share, Diluted, Total	$ 2.58	$ 1.76	$ 2.86	$ 1.74
Weighted Average Number of Shares Outstanding, Basic	56,566	56,566	56,566	56,566
Weighted Average Number of Shares Outstanding, Diluted	56,735	56,566	56,633	56,566
Construction materials
Revenue:
Revenues	$ 553,057	$ 483,221	$ 1,177,726	$ 1,060,051
Cost of revenue:
Cost of Revenue	346,298	340,609	856,606	846,965
Contracting services
Revenue:
Revenues	537,315	492,207	1,005,736	937,156
Cost of revenue:
Cost of Revenue	$ 474,685	$ 450,332	$ 900,388	$ 861,300

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Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Net Income (Loss)	$ 146,655	$ 99,657	$ 162,171	$ 98,210
Other comprehensive income:
Reclassification adjustment for loss on derivative instruments included in net income, tax	0	27	28	80
Reclassification adjustment for loss on derivative instruments included in net income, net of tax	0	82	90	246
Postretirement liability adjustment:
Postretirement liability gains (losses) arising during the period, tax	0	0	(6)	1,879
Postretirement liability gains (losses) arising during the period, net of tax	0	0	(17)	5,820
Amortization of postretirement liability losses included in net periodic benefit cost, tax	16	71	47	213
Amortization of postretirement liability losses included in net periodic benefit cost, net of tax	49	221	144	662
Postretirement liability adjustment	49	221	127	6,482
Other comprehensive income	49	303	217	6,728
Comprehensive income attributable to common stockholders	$ 146,704	$ 99,960	$ 162,388	$ 104,938

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Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Current assets:
Cash, cash equivalents and restricted cash	$ 116,159	$ 10,090
Receivables, net	491,866	210,157
Costs and estimated earnings in excess of billings on uncompleted contracts	50,545	31,145
Due from related-party	0	16,050
Inventories	314,711	323,277
Prepayments and other current assets	38,094	17,848
Total current assets	1,011,375	608,567
Noncurrent assets:
Property, plant and equipment	2,547,577	2,489,408
Less accumulated depreciation, depletion and amortization	1,248,042	1,174,195
Net property, plant and equipment	1,299,535	1,315,213
Goodwill	274,478	274,540
Other intangible assets, net	11,463	13,430
Operating lease right-of-use assets	44,309	45,873
Investments and other	39,722	36,696
Total noncurrent assets	1,669,507	1,685,752
Total assets	2,680,882	2,294,319
Current liabilities:
Long-term debt - current portion	7,082	211
Related-party notes payable - current portion	0	238,000
Accounts payable	148,977	87,370
Billings in excess of costs and estimated earnings on uncompleted contracts	58,785	39,843
Taxes payable	53,281	8,502
Accrued compensation	37,922	29,192
Due to related-party	0	20,286
Current operating lease liabilities	13,702	13,210
Other accrued liabilities	105,218	80,276
Total current liabilities	424,967	516,890
Noncurrent liabilities:
Long-term debt	675,649	427
Related-party notes payable	0	446,449
Deferred income taxes	173,989	175,804
Noncurrent operating lease liabilities	30,607	32,663
Other	132,652	93,497
Total liabilities	1,437,864	1,265,730
Stockholders' equity:
Common stock	570	800
Other paid-in capital	613,024	549,106
Retained earnings	645,185	494,661
MDU Resources Common Stock Held by Subsidiary at Cost, Value	0	(3,626)
Treasury Stock, Common, Value	(3,626)	0
Accumulated other comprehensive loss	(12,135)	(12,352)
Total stockholders' equity	1,243,018	1,028,589
Total liabilities and stockholders' equity	$ 2,680,882	$ 2,294,319
Common Stock, Shares Authorized	300,000,000	80,000
Common Stock, Par or Stated Value Per Share	$ 0.01	$ 10
Common Stock, Shares, Issued		80,000
Common Stock, Shares, Outstanding	56,566,214	80,000
MDU Resources Common Stock Held by Subsidiary at Cost, Shares		(538,921)

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Consolidated Statements of Equity - USD ($) $ in Thousands	Total	Common stock	Other paid-in capital	Retained earnings	MDU Resources' Stock Held by Subsidiary	Treasury Stock, Common	Accumulated other comprehensive loss
MDU Resources Common Stock Held by Subsidiary at Cost, Shares					(538,921)
Common stock balance (in shares) at Dec. 31, 2021		80,000
Balance at Dec. 31, 2021	$ 952,844	$ 800	$ 549,714	$ 430,446	$ (3,626)	$ 0	$ (24,490)
Treasury Stock, Common, Shares at Dec. 31, 2021						0
Net Income (Loss)	(40,010)			(40,010)
Other comprehensive income	303						303
APIC, Share-Based Payment Arrangement, Recognition and Exercise	306		333	(27)
Equity net transfers to (from) Parent	(16,408)		(3,432)	(12,976)
Common stock balance (in shares) at Mar. 31, 2022		80,000
Balance at Mar. 31, 2022	897,035	$ 800	546,615	377,433	(3,626)	$ 0	(24,187)
Treasury Stock, Common, Shares at Mar. 31, 2022						0
Common stock balance (in shares) at Dec. 31, 2021		80,000
Balance at Dec. 31, 2021	952,844	$ 800	549,714	430,446	(3,626)	$ 0	(24,490)
Treasury Stock, Common, Shares at Dec. 31, 2021						0
Net Income (Loss)	98,210
Other comprehensive income	6,728
Common stock balance (in shares) at Sep. 30, 2022		80,000
Balance at Sep. 30, 2022	1,011,316	$ 800	542,239	489,665	$ (3,626)	$ 0	(17,762)
Treasury Stock, Common, Shares at Sep. 30, 2022						0
MDU Resources Common Stock Held by Subsidiary at Cost, Shares					(538,921)
Common stock balance (in shares) at Mar. 31, 2022		80,000
Balance at Mar. 31, 2022	897,035	$ 800	546,615	377,433	$ (3,626)	$ 0	(24,187)
Treasury Stock, Common, Shares at Mar. 31, 2022						0
Net Income (Loss)	38,562			38,562
Other comprehensive income	6,122						6,122
APIC, Share-Based Payment Arrangement, Recognition and Exercise	306		333	(27)
Equity net transfers to (from) Parent	(18,037)		(5,063)	(12,974)
Common stock balance (in shares) at Jun. 30, 2022		80,000
Balance at Jun. 30, 2022	923,988	$ 800	541,885	402,994	$ (3,626)	$ 0	(18,065)
Treasury Stock, Common, Shares at Jun. 30, 2022						0
MDU Resources Common Stock Held by Subsidiary at Cost, Shares					(538,921)
Net Income (Loss)	99,657			99,657
Other comprehensive income	303						303
APIC, Share-Based Payment Arrangement, Recognition and Exercise	123		134	(11)
Equity net transfers to (from) Parent	(12,755)		220	(12,975)
Common stock balance (in shares) at Sep. 30, 2022		80,000
Balance at Sep. 30, 2022	$ 1,011,316	$ 800	542,239	489,665	$ (3,626)	$ 0	(17,762)
Treasury Stock, Common, Shares at Sep. 30, 2022						0
MDU Resources Common Stock Held by Subsidiary at Cost, Shares					(538,921)
MDU Resources Common Stock Held by Subsidiary at Cost, Shares	(538,921)				(538,921)
Common stock balance (in shares) at Dec. 31, 2022	80,000	80,000
Balance at Dec. 31, 2022	$ 1,028,589	$ 800	549,106	494,661	$ (3,626)	$ 0	(12,352)
Treasury Stock, Common, Shares at Dec. 31, 2022						0
Net Income (Loss)	(41,320)			(41,320)
Other comprehensive income	93						93
APIC, Share-Based Payment Arrangement, Recognition and Exercise	414		453	(39)
Equity net transfers to (from) Parent	(13,007)		(1,385)	(11,622)
Common stock balance (in shares) at Mar. 31, 2023		80,000
Balance at Mar. 31, 2023	$ 974,769	$ 800	548,174	441,680	(3,626)	$ 0	(12,259)
Treasury Stock, Common, Shares at Mar. 31, 2023						0
Common stock balance (in shares) at Dec. 31, 2022	80,000	80,000
Balance at Dec. 31, 2022	$ 1,028,589	$ 800	549,106	494,661	(3,626)	$ 0	(12,352)
Treasury Stock, Common, Shares at Dec. 31, 2022						0
Net Income (Loss)	162,171
Other comprehensive income	217
Common stock balance (in shares) at Sep. 30, 2023		56,997,350
Balance at Sep. 30, 2023	1,243,018	$ 570	613,024	645,185	$ 0	$ (3,626)	(12,135)
Treasury Stock, Common, Shares at Sep. 30, 2023						(431,136)
MDU Resources Common Stock Held by Subsidiary at Cost, Shares					(538,921)
Common stock balance (in shares) at Mar. 31, 2023		80,000
Balance at Mar. 31, 2023	974,769	$ 800	548,174	441,680	$ (3,626)	$ 0	(12,259)
Treasury Stock, Common, Shares at Mar. 31, 2023						0
Net Income (Loss)	56,836			56,836
Other comprehensive income	75						75
APIC, Share-Based Payment Arrangement, Recognition and Exercise	226		212	14
Transfer of parent stock held by subsidiary, shares					538,921
Transfer of parent stock held by subsidiary, Value	3,626				$ 3,626
Treasury Stock, Shares, Acquired						(431,136)
Treasury Stock, Value, Acquired, Cost Method	3,626					$ (3,626)
Stock Redeemed or Called During Period, Shares		(80,000)
Stock Redeemed or Called During Period, Value	0	$ (800)	(800)
Issuance of common stock (shares)		56,997,350
Stock Issued During Period, Value, New Issues	(26)	$ (570)	(596)
Equity net transfers to (from) Parent	62,972		62,972
Common stock balance (in shares) at Jun. 30, 2023		56,997,350
Balance at Jun. 30, 2023	1,094,852	$ 570	611,562	498,530	$ 0	$ (3,626)	(12,184)
Treasury Stock, Common, Shares at Jun. 30, 2023						(431,136)
MDU Resources Common Stock Held by Subsidiary at Cost, Shares					0
Net Income (Loss)	146,655			146,655
Other comprehensive income	49						49
APIC, Share-Based Payment Arrangement, Recognition and Exercise	1,462		1,462
Common stock balance (in shares) at Sep. 30, 2023		56,997,350
Balance at Sep. 30, 2023	$ 1,243,018	$ 570	$ 613,024	$ 645,185	$ 0	$ (3,626)	$ (12,135)
Treasury Stock, Common, Shares at Sep. 30, 2023						(431,136)
MDU Resources Common Stock Held by Subsidiary at Cost, Shares					0

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Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Operating activities:
Net Income (Loss)	$ 162,171	$ 98,210
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion and amortization	92,511	88,551
Deferred income taxes	(1,884)	5,043
Provision for credit losses	1,386	(296)
Amortization of debt issuance costs	2,425	355
Employee stock-based compensation costs	2,127	800
Pension and postretirement benefit plan net periodic benefit cost	889	981
Unrealized (gains) losses on investments	(685)	3,172
Gains on sales of assets	(3,806)	(3,575)
Changes in current assets and liabilities, net of acquisitions:
Receivables	(302,536)	(239,565)
Due from related-party	16,050	1,258
Inventories	8,566	(18,624)
Other current assets	(20,127)	835
Accounts payable	91,663	69,552
Due to related-party	(7,310)	9,829
Other current liabilities	78,006	21,786
Pension and postretirement benefit plan contributions	(1,611)	(313)
Other noncurrent changes	35,092	1,400
Net cash provided by operating activities	152,927	39,399
Investing activities:
Capital expenditures	(86,450)	(121,840)
Acquisitions, net of cash acquired	0	450
Net proceeds from sale or disposition of property and other	5,227	5,716
Investments	(1,764)	(2,226)
Net cash used in investing activities	(82,987)	(117,900)
Financing activities:
Issuance of current related-party notes, net	0	100,000
Issuance of long-term related-party notes, net	205,275	26,872
Issuance of long-term debt	700,000	0
Repayment of long-term debt	(1,891)	(206)
Debt issuance costs	(16,640)	(749)
Proceeds from issuance of common stock	(26)	0
Net transfers to Centennial	(850,589)	(42,236)
Net cash provided by financing activities	36,129	83,681
Increase in cash, cash equivalents and restricted cash	106,069	5,180
Cash, cash equivalents and restricted cash -- beginning of year	10,090	13,848
Cash, cash equivalents and restricted cash -- end of period	$ 116,159	$ 19,028

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Background	9 Months Ended
	Sep. 30, 2023
Restructuring and Related Activities [Abstract]
Background	BackgroundOn August 4, 2022, MDU Resources announced that its board of directors approved a plan to pursue the Separation of Knife River from MDU Resources. On May 31, 2023, the Separation was completed by a pro rata distribution of shares representing approximately 90 percent of Knife River's outstanding common stock to MDU Resources' stockholders. MDU Resources' stockholders received one share of Knife River common stock for every four shares of MDU Resources common stock held as of the close of business on May 22, 2023. MDU Resources retained approximately 10 percent of Knife River's common stock. The Distribution was tax-free to its stockholders for U. S. federal income tax purposes. At the time of the Separation, the net parent investment in Knife River held by Centennial was settled between the companies. As a result of the Separation, Knife River is now an independent public company trading on the New York Stock Exchange under the symbol "KNF." More information on the Separation and Distribution, as well as the Company's historical results, can be found within the Company's Registration Statement on Form 10.

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Basis of presentation

9 Months Ended

Sep. 30, 2023

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Basis of Presentation [Text Block]

Basis of presentation

The accompanying consolidated interim financial statements were prepared in accordance with 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 Registration Statement on Form 10. 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.

On May 31, 2023, the Company became a stand-alone publicly traded company. Prior to the Separation on May 31, 2023, Knife River operated as a wholly owned subsidiary of Centennial and an indirect, wholly owned subsidiary of MDU Resources and not as a stand-alone company. These consolidated financial statements and footnotes reflect the historical financial position, results of operations and cash flows of the Company as historically managed within MDU Resources for the periods prior to the completion of the Separation and reflect the financial position, results of operations and cash flows as a stand-alone company for the period after the completion of the Separation. The historical consolidated financial statements and footnotes were prepared on a “carve-out” basis in connection with the Separation and were derived from the consolidated financial statements of MDU Resources as if the Company operated on a stand-alone basis during the periods presented, and were prepared utilizing the legal entity approach in conformity with GAAP. The results for the three and nine months ended September 30, 2022, vary from the previously reported MDU Resources' construction materials and contracting services segment due to an adjustment to a cost allocation for interim periods to conform with the Company's current year accounting. This adjustment does not impact the historical annual financial statements included in the Company's Registration Statement on Form 10. This adjustment increased cost of revenue for the three months ended September 30, 2022, by $4.4 million ($3.4 million after tax) and decreased cost of revenue for the nine months ended September 30, 2022, by $1.6 million ($1.2 million after tax). The adjustment is not considered material for the three or nine months ended September 30, 2022.

The Company utilized allocations and carve-out methodologies to prepare its historical consolidated financial statements and footnotes. The consolidated financial statements and footnotes herein may not be indicative of the Company's future performance or actual expenses that would have been incurred as a stand-alone company for the periods presented.

All revenues and costs, as well as assets and liabilities, directly associated with the business activity of the Company 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 (expense). There were no amounts allocated to Knife River for the three months ended September 30, 2023, and $8.7 million was allocated for the nine months ended September 30, 2023. For the three and nine months ended September 30, 2022, there was $3.8 million and $13.4 million, respectively, allocated to Knife River. These expenses have been allocated to the Company 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 are 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.

Prior to the Separation, Knife River historically participated in Centennial’s centralized cash management program, including its overall financing arrangements. This arrangement is not reflective of the manner in which the Company would have been able to finance its operations had it been independent from MDU Resources for the period prior to the completion of the Separation. Knife River had related-party note agreements in place with Centennial for the financing of its capital needs, which are reflected as related-party notes payable on the Consolidated Balance Sheets as of December 31, 2022. The related-party notes payable to Centennial at May 30, 2023, was $889.7 million. As part of the Separation, Centennial made an equity contribution to the Company to release the Company of its obligation related to the outstanding notes payable. Also as part of the Separation, the Company entered into debt agreements and subsequently paid a dividend of $825.0 million from the debt proceeds to Centennial, which Centennial used to repay a portion of the Company's outstanding indebtedness. These transactions resulted in the Company receiving a net equity contribution of $64.7 million and is reflected as "Net transfers from Centennial and MDU Resources including separation adjustments" in the Consolidated Statement of Equity. Interest expense in the Consolidated Statements of Operations includes the allocation of interest on borrowing and funding associated with the related-party note agreements for periods prior to the Separation.

Prior to the Separation, income tax expense and tax balances in the consolidated financial statements were calculated on a separate tax return basis. The separate tax return method applies the accounting guidance for income taxes to the standalone financial statements as if the Company were a separate taxpayer and a standalone enterprise. Management believes the assumptions supporting the allocation and presentation of income taxes on a separate return basis are reasonable. As a stand-alone entity, the Company will file tax returns on its own behalf, and tax balances and effective income tax rate may differ from the amounts reported in the historical periods.

Management has also evaluated the impact of events occurring after September 30, 2023, up to the date of issuance of these consolidated interim financial statements on November 6, 2023, that would require recognition or disclosure in the Consolidated Financial Statements.

Principles of consolidation

For the pre-Separation periods, the accompanying financial statements of the Company were derived from the consolidated financial statements and accounting records of MDU Resources as if the Company and its wholly owned subsidiaries operated on a stand-alone basis during the periods presented. The consolidated financial statements were prepared in accordance with GAAP and include the accounts of the Company and its wholly owned subsidiaries. All intercompany accounts and transactions between the businesses comprising the Company have been eliminated in the accompanying consolidated financial statements. Related-party transactions between the Company and MDU Resources or Centennial for general operating activities and intercompany debt have been included in the consolidated financial statements for the pre-Separation periods. These related-party transactions were settled in cash and are reflected in the pre-Separation Consolidated Balance Sheets as “Due from related-party” or “Due to related-party” with the aggregate net effect reflected in the Consolidated Statements of Cash Flows within operating activities and “Related-party notes payable” with the aggregate net effect reflected in the Consolidated Statements of Cash Flows within financing activities.

The aggregate net effect of related-party transactions not settled in cash as part of the Separation have been reflected in the pre-Separation Consolidated Balance Sheet within “Other paid-in capital”. See Note 18 for additional information on related-party transactions.

Use of estimates

The preparation of financial statements in conformity with GAAP requires the Company 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 the Company 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.

New accounting standards

There have been no recent accounting standards that are expected to materially affect the Company.

Cash, cash equivalents and restricted cash

The Company considers all highly liquid investments with an original maturity of three months or less, when purchased, to be cash and cash equivalents. At September 30, 2023, the $116.2 million of cash, cash equivalents and restricted cash on the Consolidated Statements of Cash Flows is comprised of $84.0 million of cash and cash equivalents and $32.2 million of restricted cash. At September 30, 2022, the Company did not have any restricted cash. Restricted cash represents deposits held by Knife

River's captive insurance company that is required by state insurance regulations to remain in the captive insurance company as cash.

Seasonality of operations

Some of the Company's 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 the Company as a whole, may not be indicative of results for the full fiscal year or other future periods.

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Receivables and allowance for expected credit losses

9 Months Ended

Sep. 30, 2023

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 the Company's receivables are due in 30 days or less. The total balance of receivables past due 90 days or more was $14.4 million and $11.2 million at September 30, 2023 and December 31, 2022, respectively. Receivables were as follows:

	September 30, 2023		December 31, 2022
	(In thousands)
Trade receivables	$	236,373	$	104,347
Contract receivables	223,874		82,428
Retention receivables	37,814		28,859
Receivables, gross	498,061		215,634
Less expected credit loss	6,195		5,477
Receivables, net	$	491,866	$	210,157

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. The Company develops and documents its methodology to determine its allowance for expected credit losses. Risk characteristics used by the Company 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		North Central		All Other		Total
	(In thousands)
At December 31, 2022	$	2,045	$	1,253	$	1,278	$	839	$	62	$	5,477
Current expected credit loss provision	45		313		164		(89)		(1)		432
Less write-offs charged against the allowance	1		68		18		—		—		87
At March 31, 2023	$	2,089	$	1,498	$	1,424	$	750	$	61	$	5,822
Current expected credit loss provision	9		74		631		(132)		1		583
Less write-offs charged against the allowance	18		512		3		—		2		535
At June 30, 2023	$	2,080	$	1,060	$	2,052	$	618	$	60	$	5,870
Current expected credit loss provision	46		242		(152)		215		20		371
Less write-offs charged against the allowance	26		4		13		3		—		46
At September 30, 2023	$	2,100	$	1,298	$	1,887	$	830	$	80	$	6,195

	Pacific		Northwest		Mountain		North Central		All Other		Total
	(In thousands)
At December 31, 2021	$	2,052	$	512	$	1,610	$	1,152	$	80	$	5,406
Current expected credit loss provision	1		(125)		(130)		6		(5)		(253)
Less write-offs charged against the allowance	1		20		3		1		1		26
At March 31, 2022	$	2,052	$	367	$	1,477	$	1,157	$	74	$	5,127
Current expected credit loss provision	11		58		(17)		(37)		(3)		12
Less write-offs charged against the allowance	—		56		4		47		2		109
At June 30, 2022	$	2,063	$	369	$	1,456	$	1,073	$	69	$	5,030
Current expected credit loss provision	(6)		194		(111)		(141)		9		(55)
Less write-offs charged against the allowance	9		7		40		4		16		76
At September 30, 2022	$	2,048	$	556	$	1,305	$	928	$	62	$	4,899

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Inventories

9 Months Ended

Sep. 30, 2023

Inventory Disclosure [Abstract]

Inventories

Inventories

Inventories on the Consolidated Balance Sheets were as follows:

	September 30, 2023		December 31, 2022
	(In thousands)
Finished products	$	213,702	$	211,496
Raw materials	63,156		78,571
Supplies and parts	37,853		33,210
Total	$	314,711	$	323,277

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 the Company's 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.

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Earnings per share

9 Months Ended

Sep. 30, 2023

Earnings Per Share [Abstract]

Earnings per share

Earnings per share

The calculation for basic and diluted earnings per share for any period presented prior to the Separation are based on the number of shares outstanding on May 31, 2023, the Separation and Distribution date. For periods prior to the Separation, it is assumed that there are no dilutive equity instruments as there were no Knife River stock-based awards outstanding at the time.

Basic earnings per share is computed by dividing net income by the weighted average number of shares of common stock outstanding during the applicable period. Diluted earnings 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 restricted stock units. Weighted average common shares outstanding is comprised of issued shares of 56,997,350 less shares held in treasury of 431,136, as described in Note 6. Basic and diluted earnings 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				Nine Months Ended
	September 30,				September 30,
	2023		2022		2023		2022
	(In thousands, except per share amounts)
Net income	$	146,655	$	99,657	$	162,171	$	98,210
Weighted average common shares outstanding - basic	56,566		56,566		56,566		56,566
Effect of dilutive restricted stock units	169		—		67		—
Weighted average common shares outstanding - diluted	56,735		56,566		56,633		56,566
Shares excluded from the calculation of diluted earnings per share	—		—		—		—
Net income per share - basic	$	2.59	$	1.76	$	2.87	$	1.74
Net income per share - diluted	$	2.58	$	1.76	$	2.86	$	1.74

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Equity

9 Months Ended

Sep. 30, 2023

Equity [Abstract]

Equity

Equity

On May 31, 2023, the Company issued 56,997,350 shares of common stock with a par value of $0.01 in connection with the Separation.

The Company historically held 538,921 shares of MDU Resources common stock through one of its subsidiaries. The historical shares are presented as MDU Resources' stock held by subsidiary on the Consolidated Statement of Equity. In connection with the Separation, Knife River entered into an agreement with MDU Resources to transfer the stock of MDU Resources held by its subsidiary to MDU Resources in exchange for 431,136 shares of Knife River common stock. The number of shares transferred to Knife River was based on the value of the stock at the time of the Separation. The historical MDU Resources common stock held by subsidiary at cost of $3.6 million at September 30, 2023, on the Consolidated Balance Sheets reflects the value of the MDU Resources common stock at the time it was granted to Knife River's subsidiary and will remain at the historical value since the exchange was between related parties. The 431,136 shares of Knife River common stock are presented as Treasury stock held at cost in the Consolidated Balance Sheet and reduce the number of common stock shares outstanding.

Stock-based compensation

Prior to the Separation, key employees of the Company participated in various stock-based compensation plans authorized and managed by MDU Resources. All awards granted under the plans were based on MDU Resources' common shares, however, Knife River recognized the expense for its participants in its financial statements.

At the time of the Separation, each outstanding MDU Resources time-vested restricted stock unit and performance share award held by a Knife River employee was converted into Knife River time-vested restricted stock units. The converted awards will continue to vest over the original vesting period, which is generally three years from the grant date. All performance share awards that were converted at the time of the Separation were first adjusted using a combined performance factor based on MDU Resources' actual performance as of December 31, 2022. The number of restricted stock units was determined by taking the closing per share price of MDU Resources on May 31, 2023, and dividing by the closing per share price of Knife River on June 1, 2023. The ratio used to convert the MDU Resources' share-based awards was designed to preserve the aggregate intrinsic value of the award immediately after the Separation when compared to the aggregate intrinsic value of the award immediately prior to the Separation. The existing unvested stock-based awards issued through MDU Resources' stock-based compensation plans were modified in connection with the Separation to maintain an equivalent value immediately before and after Separation. The impact of this modification will be recorded over the remaining vesting periods and was not material to the Company's stock-based compensation expense for the three or nine months ended September 30, 2023.

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Accumulated other comprehensive loss

9 Months Ended

Sep. 30, 2023

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)
At 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)
Other comprehensive loss before reclassification	—		—		—
Amounts reclassified from accumulated other comprehensive loss	—		49		49
Net current-period other comprehensive income	—		49		49
At September 30, 2023	$	—	$	(12,135)	$	(12,135)

	Net Unrealized Loss on Derivative  Instruments  Qualifying as Hedges		Postretirement  Liability Adjustment		Total Accumulated  Other Comprehensive  Loss
	(In thousands)
At December 31, 2021	$	(418)	$	(24,072)	$	(24,490)
Amounts reclassified from accumulated other comprehensive loss	82		221		303
Net current-period other comprehensive income	82		221		303
At March 31, 2022	$	(336)	$	(23,851)	$	(24,187)
Other comprehensive income before reclassification	—		5,820		5,820
Amounts reclassified from accumulated other comprehensive loss	82		220		302
Net current-period other comprehensive income	82		6,040		6,122
At June 30, 2022	$	(254)	$	(17,811)	$	(18,065)
Amounts reclassified from accumulated other comprehensive loss	82		221		303
Net current-period other comprehensive income	82		221		303
At September 30, 2022	$	(172)	$	(17,590)	$	(17,762)

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				Nine Months Ended				Location on Consolidated Statements of Operations
	September 30,				September 30,
	2023		2022		2023		2022
	(In thousands)
Reclassification adjustment for loss on derivative income	$	—	$	(109)	$	(118)	$	(326)	Interest expense
	—		27		28		80		Income taxes
	—		(82)		(90)		(246)
Amortization of postretirement liability losses included in net periodic benefit cost	(65)		(292)		(191)		(875)		Other income
	16		71		47		213		Income taxes
	(49)		(221)		(144)		(662)
Total reclassifications	$	(49)	$	(303)	$	(234)	$	(908)

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Revenue from contracts with customers

9 Months Ended

Sep. 30, 2023

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. The Company is considered an agent for certain taxes collected from customers. As such, the Company presents 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. The Company believes 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 15.

Three Months Ended September 30, 2023	Pacific		Northwest		Mountain		North Central		All Other		Total
	(In thousands)
Aggregates	$	33,624	$	57,398	$	39,519	$	47,656	$	15,388	$	193,585
Ready-mix concrete	39,861		46,785		44,053		73,183		12,157		216,039
Asphalt	14,050		43,462		59,673		95,053		10,539		222,777
Other	81,081		4,497		11		10,211		118,312		214,112
Contracting services public-sector	32,632		68,316		135,700		181,779		23,483		441,910
Contracting services private-sector	17,745		25,144		43,944		8,526		46		95,405
Internal sales	(37,566)		(36,683)		(68,178)		(111,288)		(39,741)		(293,456)
Revenues from contracts with customers	$	181,427	$	208,919	$	254,722	$	305,120	$	140,184	$	1,090,372

Three Months Ended September 30, 2022	Pacific		Northwest		Mountain		North Central		All Other		Total
	(In thousands)
Aggregates	$	28,695	$	52,614	$	31,258	$	45,039	$	14,197	$	171,803
Ready-mix concrete	35,395		45,600		37,334		64,496		16,082		198,907
Asphalt	10,935		45,110		45,553		96,830		7,133		205,561
Other	63,002		4,447		12		8,711		90,539		166,711
Contracting services public-sector	30,529		78,664		100,298		184,266		18,874		412,631
Contracting services private-sector	14,512		20,424		38,755		5,664		221		79,576
Internal sales	(30,710)		(42,627)		(49,089)		(110,700)		(26,635)		(259,761)
Revenues from contracts with customers	$	152,358	$	204,232	$	204,121	$	294,306	$	120,411	$	975,428

Nine Months Ended September 30, 2023	Pacific		Northwest		Mountain		North Central		All Other		Total
	(In thousands)
Aggregates	$	79,768	$	147,937	$	78,051	$	81,999	$	35,767	$	423,522
Ready-mix concrete	106,531		125,273		92,929		139,369		33,604		497,706
Asphalt	21,640		84,908		89,955		141,942		22,888		361,333
Other	168,104		11,513		21		22,703		193,528		395,869
Contracting services public-sector	53,450		138,621		244,320		280,853		61,293		778,537
Contracting services private-sector	37,220		80,258		94,706		13,884		1,131		227,199
Internal sales	(75,345)		(84,937)		(108,888)		(167,055)		(64,479)		(500,704)
Revenues from contracts with customers	$	391,368	$	503,573	$	491,094	$	513,695	$	283,732	$	2,183,462

Nine Months Ended September 30, 2022	Pacific		Northwest		Mountain		North Central		All Other		Total
	(In thousands)
Aggregates	$	72,088	$	129,752	$	67,388	$	75,718	$	40,892	$	385,838
Ready-mix concrete	98,520		121,079		84,950		124,026		46,959		475,534
Asphalt	26,909		79,801		77,021		141,595		19,886		345,212
Other	143,140		11,804		26		20,766		152,757		328,493
Contracting services public-sector	63,450		141,783		202,495		275,797		52,933		736,458
Contracting services private-sector	38,922		60,321		91,783		8,809		863		200,698
Internal Sales	(76,911)		(84,733)		(90,654)		(162,342)		(60,386)		(475,026)
Revenues from contracts with customers	$	366,118	$	459,807	$	433,009	$	484,369	$	253,904	$	1,997,207

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Uncompleted Contracts

9 Months Ended

Sep. 30, 2023

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:

	September 30, 2023		December 31, 2022		Change		Location on Consolidated Balance Sheets
	(In thousands)
Contract assets	$	50,545	$	31,145	$	19,400	Costs and estimated earnings in excess of billings on uncompleted contracts
Contract liabilities	(58,785)		(39,843)		(18,942)		Billings in excess of costs and estimated earnings on uncompleted contracts
Net contract liabilities	$	(8,240)	$	(8,698)	$	458

The Company recognized $3.4 million and $35.1 million in revenue for the three and nine months ended September 30, 2023, respectively, which was previously included in contract liabilities at December 31, 2022. The Company recognized $3.0 million and $29.2 million in revenue for the three and nine months ended September 30, 2022, respectively, which was previously included in contract liabilities at December 31, 2021.

The Company recognized a net increase in revenues of $12.1 million and $10.6 million for the three and nine months ended September 30, 2023, respectively, from performance obligations satisfied in prior periods. The Company recognized a net increase in revenues of $4.9 million and $10.4 million for the three and nine months ended September 30, 2022, respectively, from performance obligations satisfied in prior periods.

Remaining performance obligations

The remaining performance obligations, also referred to as backlog, include unrecognized revenues that the Company reasonably expects 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 the Company's contracts for contracting services have an original duration of less than one year.

At September 30, 2023, the Company's remaining performance obligations were $732.2 million. The Company expects to recognize the following revenue amounts in future periods related to these remaining performance obligations: $677.7 million within the next 12 months or less; $38.5 million within the next 13 to 24 months; and $16.0 million in 25 months or more.

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Goodwill and other intangible assets

9 Months Ended

Sep. 30, 2023

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, 2023		Goodwill Acquired During the Year		Measurement Period Adjustments		Balance at September 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
All Other	42,528		—		—		42,528
Total	$	274,540	$	—	$	(62)	$	274,478

Other amortizable intangible assets were as follows:

	September 30, 2023		December 31, 2022
	(In thousands)
Customer relationships	$	18,540	$	18,540
Less accumulated amortization	8,668		7,367
	9,872		11,173
Noncompete agreements	4,039		4,039
Less accumulated amortization	3,358		2,985
	681		1,054
Other	2,479		5,279
Less accumulated amortization	1,569		4,076
	910		1,203
Total	$	11,463	$	13,430

Amortization expense for amortizable intangible assets for the three and nine months ended September 30, 2023, was $647,000 and $2.0 million, respectively. Amortization expense for amortizable intangible assets for the three and nine months ended September 30, 2022, was $729,000 and $2.1 million, respectively. Estimated amortization expense for identifiable intangible assets as of September 30, 2023, was:

	Remainder of 2023		2024		2025		2026		2027		Thereafter
	(In thousands)
Amortization expense	$	590	$	2,157	$	2,042	$	1,739	$	1,717	$	3,218

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Fair value measurements

9 Months Ended

Sep. 30, 2023

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 ASC 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.

The Company measures its investments in certain fixed-income and equity securities at fair value with changes in fair value recognized in income. The Company anticipates using these investments, which consist of insurance contracts, to satisfy its obligations under its unfunded, nonqualified defined benefit and defined contribution plans for the Company's 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 $23.5 million and $20.1 million at September 30, 2023 and December 31, 2022, respectively, are classified as investments on the Consolidated Balance Sheets. The net unrealized loss on these investments was $597,000 for the three months ended September 30, 2023 and the net unrealized gain on these investments was $685,000 for the nine months ended September 30, 2023. The net unrealized loss on these investments was $541,000 and $3.2 million for the three and nine months ended September 30, 2022, 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.

As part of the Separation, the Company retired certain insurance contracts used to satisfy its obligations under its unfunded, nonqualified defined contribution plan for the Company's executive officers and certain key management employees. The proceeds of the retired contracts totaled $4.8 million, which were used to purchase life insurance policies and re-invested in fixed-income and equity securities in the third quarter of 2023.

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

	Fair Value Measurements at September 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 September 30, 2023
	(In thousands)
Assets:
Money market funds	$	—	$	3,199	$	—	$	3,199
Insurance contracts*	—		23,483		—		23,483
Total assets measured at fair value	$	—	$	26,682	$	—	$	26,682

*    The insurance contracts invest approximately 41 percent in fixed-income investments, 19 percent in cash equivalents, 18 percent in common stock of large-cap companies, 8 percent in common stock of mid-cap companies, 8 percent target date investments, 5 percent in common stock of small-cap companies and 1 percent in international investments.

	Fair Value Measurements at December 31, 2022, 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, 2022
	(In thousands)
Assets:
Money market funds	$	—	$	2,448	$	—	$	2,448
Insurance contracts*	—		20,083		—		20,083
Total assets measured at fair value	$	—	$	22,531	$	—	$	22,531

*    The insurance contracts invest approximately 63 percent in fixed-income investments, 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, 6 percent in target date investments and 2 percent in cash equivalents.

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 are 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 the Company believes 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.

The Company applies the provisions of the fair value measurement standard to its 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. The Company reviews the carrying value of its long-lived assets, excluding goodwill, whenever events or changes in circumstances indicate that such carrying amounts may not be recoverable.

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:

	September 30, 2023
	(In thousands)
Carrying amount	$	698,747
Fair value	$	700,687

The carrying amounts of the Company's remaining financial instruments included in current assets and current liabilities approximate their fair values.

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Debt

9 Months Ended

Sep. 30, 2023

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, the Company must be in compliance with the applicable covenants and certain other conditions, all of which management believes the Company, as applicable, was in compliance with at September 30, 2023. In the event the Company does not comply with the applicable covenants and other conditions, alternative sources of funding may need to be pursued.

On April 25, 2023, the Company issued $425.0 million of 7.75 percent senior notes due May 1, 2031, pursuant to an indenture.

On May 31, 2023, the Company entered into a senior secured credit agreement consisting of a $275.0 million term loan and a $350.0 million revolving credit facility. As of September 30, 2023, the Company had no outstanding borrowings against the revolving credit facility. Each debt facility has a SOFR-based interest rate and a maturity date of May 31, 2028. The term loan has a mandatory annual amortization of 2.50 percent for years one and two, 5.00 percent for years three and four, and 7.50 percent in the fifth year. The agreement contains customary covenants and provisions, including a covenant of Knife River not to permit, at any time, the ratio of total debt to trailing twelve month EBITDA to be greater than 4.75 to 1.00. The agreement also contains an interest coverage ratio covenant stating that Knife River’s trailing twelve month EBITDA to interest expense is to be no less than 2.25 to 1.00. The covenants also include restrictions on the sale of certain assets, loans and investments.

Knife River's wholly owned subsidiary companies, subject to certain exclusions and exceptions, are named as subsidiary guarantors of the senior notes and the senior secured credit agreement. In addition, Knife River has pledged substantially all of its assets as collateral, subject to certain exclusions and exceptions, for the senior secured credit agreement.

Long-term debt

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

	Weighted Average Interest Rate at September 30, 2023		September 30, 2023
			(In thousands)
Term loan agreement due on May 31, 2028	7.52	%	$	273,281
Senior notes due on May 1, 2031	7.75	%	425,000
Other notes due on January 1, 2061	—	%	466
Less unamortized debt issuance costs			16,016
Total long-term debt			682,731
Less current maturities			7,082
Net long-term debt			$	675,649

Schedule of Debt Maturities Long-term debt maturities, which excludes unamortized debt issuance costs, at September 30, 2023, were as follows:

	Remainder of 2023		2024		2025		2026		2027		Thereafter
	(In thousands)
Long-term debt maturities	$	1,719	$	7,082	$	10,520	$	13,802	$	17,187	$	648,437

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Income Taxes

9 Months Ended

Sep. 30, 2023

Income Tax Disclosure [Abstract]

Income Tax Disclosure

Income taxes

Post-Separation, the income tax provisions are calculated based on Knife River's operating footprint, as well as tax return elections and assertions. Current income tax liabilities including amounts for unrecognized tax benefits related to the Company's activities included in MDU Resources' income tax returns were deemed to be immediately settled with MDU Resources' final settlement allocation process as dictated by the MDU Resources' Tax Sharing Agreement.

Prior to the Separation, income tax expense and tax balances in the consolidated financial statements were calculated on a separate tax return basis. The separate tax return method applies the accounting guidance for income taxes to the stand-alone financial statements as if the Company were a separate taxpayer and a stand-alone enterprise. Management believes the assumptions supporting the allocation and presentation of income taxes on a separate return basis are reasonable. As a stand-alone entity, the Company will file tax returns on its own behalf, and tax balances and effective income tax rate may differ from the amounts reported in the historical periods.

Income tax expense is based on reported income before income taxes. Deferred income taxes reflect the tax effect of temporary differences between asset and liability amounts that are recognized for financial reporting purposes and the amounts that are recognized for income tax purposes. These deferred taxes are measured by applying currently enacted tax laws.

Valuation allowances are recognized to reduce deferred tax assets to the amount that will more likely than not be realized. In assessing the need for a valuation allowance, management considers all available evidence for each jurisdiction including past operating results, estimates of future taxable income and the feasibility of ongoing tax planning strategies and actions. When there is a change in determination as to the amount of deferred tax assets that can be realized, the valuation allowance is adjusted with a corresponding impact to provision for income taxes in the period in which such determination is made.

The Company's cash tax payments for the year may vary significantly from prior years as a result of the timing of the Separation and the seasonality of the Company's business.

Other Tax Matters

Tax Matters Agreement In connection with the Separation, the Company entered into a tax matters agreement with MDU Resources. The tax matters agreement governs the respective rights, responsibilities, and obligations between the Company and MDU Resources after the Separation with respect to tax liabilities and benefits, tax attributes, tax returns, tax contests and other tax sharing regarding U.S. federal, state and local income taxes, other tax matters and related tax returns.

Tax Refunds and Attributes The tax matters agreement provides for the allocation of certain pre-closing tax attributes between the Company and MDU Resources. Tax attributes will be allocated in accordance with the principles set forth in the MDU Resources' Tax Sharing Agreement, then existing, unless otherwise required by law. Under the tax matters agreement, the Company will be entitled to refunds for taxes for which the Company is responsible.

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Cash flow information

9 Months Ended

Sep. 30, 2023

Supplemental Cash Flow Information [Abstract]

Cash flow information

Cash flow information

Cash expenditures for interest and income taxes were as follows:

	Nine Months Ended
	September 30,
	2023		2022
	(In thousands)
Interest paid, net	$	32,028	$	19,472
Income taxes paid, net	$	22,183	$	23,163

Noncash investing and financing transactions were as follows:

	Nine Months Ended
	September 30,
	2023		2022
	(In thousands)
Right-of-use assets obtained in exchange for new operating lease liabilities	$	9,717	$	5,851
Property, plant and equipment additions in accounts payable	$	2,832	$	4,884
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	$	—

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Business segment data

9 Months Ended

Sep. 30, 2023

Segment Reporting [Abstract]

Business segment data

Business segment data

The Company focuses on the vertical integration of its products and services by offering customers a single source for construction materials and related contracting services. The Company operates in 14 states across the United States. Its operating segments include: Pacific, Northwest, Mountain, North Central, South and Energy Services. The operating segments are organized by geographic region in the United States due to the cyclical nature of the construction work performed. The Company’s reportable segments are those that are based on the Company’s method of internal reporting and management of the business and are Pacific, Northwest, Mountain and North Central. The South and Energy Services operating segments do not meet the criteria to be reportable segments and, as such, are combined with its corporate services in All Other. Each segment is led by a segment president that reports to the Company’s chief operating officer. The chief operating officer works directly with the chief executive officer, the chief operating decision maker, to evaluate the performance of the segments using EBITDA and the allocation of resources.

All of the reportable segments mine, process and sell construction aggregates (crushed stone and sand and gravel); produce and sell asphalt; and produce and sell ready-mix concrete, as well as in some segments the sale of merchandise and other building materials and related services, as well as vertically integrating their contracting services to support the aggregate-based product lines including heavy-civil construction, asphalt and concrete paving, and site development and grading, and in some segments the manufacturing of prestressed concrete products. The Pacific segment and All Other also produce and sell liquid asphalt products and the Pacific segment sells cement. Although not common to all locations, within All Other is the sale of merchandise and other building materials and related services.

The information below follows the same accounting policies as described in the audited financial statements and notes included in the Company's Registration Statement on Form 10. Information on the Company's segments was as follows:

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2023		2022		2023		2022
	(In thousands)
External operating revenues:
Pacific	$	181,427	$	152,358	$	391,368	$	366,118
Northwest	208,919		204,232		503,573		459,807
Mountain	254,722		204,121		491,094		433,009
North Central	305,120		294,306		513,695		484,369
All Other	140,184		120,411		283,732		253,904
Total external operating revenues	$	1,090,372	$	975,428	$	2,183,462	$	1,997,207
Intersegment operating revenues:
Pacific	$	37,566	$	30,710	$	75,345	$	76,911
Northwest	36,683		42,627		84,937		84,733
Mountain	68,178		49,089		108,888		90,654
North Central	111,288		110,700		167,055		162,342
All Other	39,741		26,635		64,479		60,386
Total intersegment operating revenues	$	293,456	$	259,761	$	500,704	$	475,026
EBITDA:
Pacific	$	37,558	$	24,563	$	56,486	$	45,194
Northwest	48,867		43,797		102,711		79,774
Mountain	60,473		39,644		86,486		60,244
North Central	70,508		58,584		71,402		50,424
All Other	23,994		5,500		35,323		5,578
Total segment EBITDA	$	241,400	$	172,088	$	352,408	$	241,214

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

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2023		2022		2023		2022
	(In thousands)
Total reportable segment operating revenues	$	1,203,903	$	1,088,143	$	2,335,955	$	2,157,943
Other operating revenues	179,925		147,046		348,211		314,290
Less:
Elimination of intersegment operating revenues	293,456		259,761		500,704		475,026
Total consolidated operating revenues	$	1,090,372	$	975,428	$	2,183,462	$	1,997,207

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

	Three Months Ended				Nine Months Ended
	Sept. 30,				Sept. 30,
	2023		2022		2023		2022
	(In thousands)
Total EBITDA for reportable segments	$	217,406	$	166,588	$	317,085	$	235,636
Other EBITDA	23,994		5,500		35,323		5,578
Less:
Depreciation, depletion and amortization	31,752		30,450		92,511		88,551
Interest expense, net*	14,774		8,817		41,399		21,506
Total consolidated income before income taxes	$	194,874	$	132,821	$	218,498	$	131,157
*Interest, net is interest expense net of interest income.

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Employee benefit plans

9 Months Ended

Sep. 30, 2023

Retirement Benefits [Abstract]

Employee benefit plans

Employee benefit plans

The Company has noncontributory qualified defined benefit pension plans and other postretirement benefit plans for certain eligible employees. Prior to the Separation, Knife River was a participant in the MDU Resources postretirement benefit plan. The Company historically treated its share of the postretirement obligation under that plan as a single employer plan in accordance with ASC 715 - Compensation - Retirement Benefits and recorded the funded status and net periodic benefit cost associated with Knife River employees at Knife River. In connection with the Separation, effective June 1, 2023, Knife River established a new, stand-alone postretirement plan comparable to that of MDU Resources and transferred its obligations of $1.5 million for current participants (inclusive of employees that transferred to the Company from MDU Resources) to that plan. The Company's pension benefit plans were stand-alone for Knife River prior to the Separation.

Components of net periodic benefit cost for the Company's pension benefit plans were as follows:

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2023		2022		2023		2022
	(In thousands)
Components of net periodic benefit cost:
Interest cost	$	408	$	282	$	1,224	$	846
Expected return on assets	(450)		(493)		(1,350)		(1,479)
Amortization of net actuarial loss	128		214		384		642
Net periodic benefit cost	$	86	$	3	$	258	$	9

Components of net periodic benefit cost for the Company's other postretirement benefit plans were as follows:

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2023		2022		2023		2022
	(In thousands)
Components of net periodic benefit cost:
Service cost	$	91	$	131	$	270	$	393
Interest cost	180		128		541		384
Expected return on assets	—		(3)		12		(9)
Amortization of prior service credit	(20)		(20)		(60)		(60)
Amortization of net actuarial (gain) loss	(43)		88		(132)		264
Net periodic benefit cost	$	208	$	324	$	631	$	972

The components of net periodic benefit cost, other than the service cost component, are included in other income on the Consolidated Statements of Operations. The service cost component is included in selling, general and administrative expenses on the Consolidated Statements of Operations.

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Contingencies

9 Months Ended

Sep. 30, 2023

Commitments and Contingencies Disclosure [Abstract]

Contingencies

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. The Company accrues 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. The Company does 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, the Company discloses 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 September 30, 2023 and December 31, 2022, the Company accrued contingent liabilities as a result of litigation, which have not been discounted, of $645,000 and $1.0 million, respectively. At December 31, 2022, the Company also recorded corresponding insurance receivables of $325,000 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. The Company 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 Company's environmental matters that were previously reported in the audited financial statements and notes included in the Company's Registration Statement on Form 10.

Guarantees

Certain subsidiaries of the Company 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 September 30, 2023, 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 September 30, 2023.

Certain subsidiaries of the Company have outstanding letters of credit to third parties related to insurance policies, cement purchases and other agreements. At September 30, 2023, the fixed maximum amounts guaranteed under these letters of credit aggregated $4.8 million. At September 30, 2023, the amounts of scheduled expiration of the maximum amounts guaranteed under these letters of credit aggregate to $4.0 million in 2023 and $771,000 in 2024. There were no amounts outstanding under the previously mentioned letters of credit at September 30, 2023.

In the normal course of business, the Company has surety bonds related to contracts for contracting services, reclamation obligations and insurance policies of its subsidiaries. In the event a subsidiary of the Company 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 is expected to expire within the next 12 months; however, the Company will likely continue to enter into surety bonds for its subsidiaries in the future. At September 30, 2023, approximately $619.2 million of surety bonds were outstanding, which were not reflected on the Consolidated Balance Sheet.

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Related Party Disclosures

9 Months Ended

Sep. 30, 2023

Related Party Transactions [Abstract]

Related Party Transactions Disclosure

Related-party transactions

Transition services agreements

As part of the Separation, MDU Resources is providing transition services to the Company and the Company is providing transition services to MDU Resources in accordance with the Transition Services Agreement entered into on May 30, 2023. For the three and nine months ended September 30, 2023, the Company paid $1.3 million and $1.9 million, respectively, related to these activities, which were reflected in selling, general and administrative expenses on the Consolidated Statements of Operations. For the three and nine months ended September 30, 2023, the Company received $407,000 and $684,000, respectively, related to these activities, which were reflected in other income (expense) on the Consolidated Statements of Operations. The majority of the transition services are expected to be completed over a period of one year, but no longer than two years after the Separation.

Related-party notes payable

The related-party notes payable to Centennial at May 30, 2023, was $889.7 million. As part of the Separation, Centennial made an equity contribution to the Company to release the Company of its obligation related to the outstanding notes payable. Also as part of the Separation, the Company issued $425.0 million of 7.75 percent senior notes due May 1, 2031, a credit agreement consisting of a $275.0 million term loan and a $350.0 million revolving credit facility, of which $190.0 million was drawn down at the time of the Separation. On May 31, 2023, the Company paid a dividend of $825.0 million from these proceeds to Centennial, which Centennial used to repay a portion of the Company's outstanding indebtedness. These transactions resulted in the Company receiving a net equity contribution of $64.7 million and is reflected as "Net transfers from Centennial and MDU Resources including separation adjustments" in the Consolidated Statement of Equity. Refer to Note 12 for additional information on the debt facilities entered into in connection with the Separation.

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

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Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2023	Sep. 30, 2022
Pay vs Performance Disclosure
Net Income (Loss)	$ 146,655	$ 56,836	$ (41,320)	$ 99,657	$ 38,562	$ (40,010)	$ 162,171	$ 98,210

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Insider Trading Arrangements	3 Months Ended
	Sep. 30, 2023
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

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Basis of presentation (Policies)

9 Months Ended

Sep. 30, 2023

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Basis of presentation

The accompanying consolidated interim financial statements were prepared in accordance with 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 Registration Statement on Form 10. 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.

On May 31, 2023, the Company became a stand-alone publicly traded company. Prior to the Separation on May 31, 2023, Knife River operated as a wholly owned subsidiary of Centennial and an indirect, wholly owned subsidiary of MDU Resources and not as a stand-alone company. These consolidated financial statements and footnotes reflect the historical financial position, results of operations and cash flows of the Company as historically managed within MDU Resources for the periods prior to the completion of the Separation and reflect the financial position, results of operations and cash flows as a stand-alone company for the period after the completion of the Separation. The historical consolidated financial statements and footnotes were prepared on a “carve-out” basis in connection with the Separation and were derived from the consolidated financial statements of MDU Resources as if the Company operated on a stand-alone basis during the periods presented, and were prepared utilizing the legal entity approach in conformity with GAAP. The results for the three and nine months ended September 30, 2022, vary from the previously reported MDU Resources' construction materials and contracting services segment due to an adjustment to a cost allocation for interim periods to conform with the Company's current year accounting. This adjustment does not impact the historical annual financial statements included in the Company's Registration Statement on Form 10. This adjustment increased cost of revenue for the three months ended September 30, 2022, by $4.4 million ($3.4 million after tax) and decreased cost of revenue for the nine months ended September 30, 2022, by $1.6 million ($1.2 million after tax). The adjustment is not considered material for the three or nine months ended September 30, 2022.

The Company utilized allocations and carve-out methodologies to prepare its historical consolidated financial statements and footnotes. The consolidated financial statements and footnotes herein may not be indicative of the Company's future performance or actual expenses that would have been incurred as a stand-alone company for the periods presented.

All revenues and costs, as well as assets and liabilities, directly associated with the business activity of the Company 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 (expense). There were no amounts allocated to Knife River for the three months ended September 30, 2023, and $8.7 million was allocated for the nine months ended September 30, 2023. For the three and nine months ended September 30, 2022, there was $3.8 million and $13.4 million, respectively, allocated to Knife River. These expenses have been allocated to the Company 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 are 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.

Prior to the Separation, Knife River historically participated in Centennial’s centralized cash management program, including its overall financing arrangements. This arrangement is not reflective of the manner in which the Company would have been able to finance its operations had it been independent from MDU Resources for the period prior to the completion of the Separation. Knife River had related-party note agreements in place with Centennial for the financing of its capital needs, which are reflected as related-party notes payable on the Consolidated Balance Sheets as of December 31, 2022. The related-party notes payable to Centennial at May 30, 2023, was $889.7 million. As part of the Separation, Centennial made an equity contribution to the Company to release the Company of its obligation related to the outstanding notes payable. Also as part of the Separation, the Company entered into debt agreements and subsequently paid a dividend of $825.0 million from the debt proceeds to Centennial, which Centennial used to repay a portion of the Company's outstanding indebtedness. These transactions resulted in the Company receiving a net equity contribution of $64.7 million and is reflected as "Net transfers from Centennial and MDU Resources including separation adjustments" in the Consolidated Statement of Equity. Interest expense in the Consolidated Statements of Operations includes the allocation of interest on borrowing and funding associated with the related-party note agreements for periods prior to the Separation.

Prior to the Separation, income tax expense and tax balances in the consolidated financial statements were calculated on a separate tax return basis. The separate tax return method applies the accounting guidance for income taxes to the standalone financial statements as if the Company were a separate taxpayer and a standalone enterprise. Management believes the assumptions supporting the allocation and presentation of income taxes on a separate return basis are reasonable. As a stand-alone entity, the Company will file tax returns on its own behalf, and tax balances and effective income tax rate may differ from the amounts reported in the historical periods.

Management has also evaluated the impact of events occurring after September 30, 2023, up to the date of issuance of these consolidated interim financial statements on November 6, 2023, that would require recognition or disclosure in the Consolidated Financial Statements.

Consolidation, Policy

For the pre-Separation periods, the accompanying financial statements of the Company were derived from the consolidated financial statements and accounting records of MDU Resources as if the Company and its wholly owned subsidiaries operated on a stand-alone basis during the periods presented. The consolidated financial statements were prepared in accordance with GAAP and include the accounts of the Company and its wholly owned subsidiaries. All intercompany accounts and transactions between the businesses comprising the Company have been eliminated in the accompanying consolidated financial statements. Related-party transactions between the Company and MDU Resources or Centennial for general operating activities and intercompany debt have been included in the consolidated financial statements for the pre-Separation periods. These related-party transactions were settled in cash and are reflected in the pre-Separation Consolidated Balance Sheets as “Due from related-party” or “Due to related-party” with the aggregate net effect reflected in the Consolidated Statements of Cash Flows within operating activities and “Related-party notes payable” with the aggregate net effect reflected in the Consolidated Statements of Cash Flows within financing activities. The aggregate net effect of related-party transactions not settled in cash as part of the Separation have been reflected in the pre-Separation Consolidated Balance Sheet within “Other paid-in capital”. See Note 18 for additional information on related-party transactions.

Use of Estimates, Policy

The preparation of financial statements in conformity with GAAP requires the Company 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 the Company 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.

New accounting standards

There have been no recent accounting standards that are expected to materially affect the Company.

Cash and Cash Equivalents, Restricted Cash and Cash Equivalents, Policy

The Company considers all highly liquid investments with an original maturity of three months or less, when purchased, to be cash and cash equivalents.

Seasonality of operations

Some of the Company's 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.

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Receivables and allowance for expected credit losses (Policies)	9 Months Ended
	Sep. 30, 2023
Credit Loss [Abstract]
Accounts receivable and allowance for doubtful accounts	Receivables consist primarily of trade and contract receivables for the sale of goods and services net of expected credit losses. A majority of the Company's receivables are due in 30 days or less.
Expected credit loss	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. The Company develops and documents its methodology to determine its allowance for expected credit losses. Risk characteristics used by the Company 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.

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Earnings per share (Policies)	9 Months Ended
	Sep. 30, 2023
Earnings Per Share [Abstract]
Earnings per share	Basic earnings per share is computed by dividing net income by the weighted average number of shares of common stock outstanding during the applicable period. Diluted earnings 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 restricted stock units.

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Revenue from contracts with customers (Policies)	9 Months Ended
	Sep. 30, 2023
Revenue from Contract with Customer [Abstract]
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. The Company is considered an agent for certain taxes collected from customers. As such, the Company presents 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.

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Fair value disclosures (Policies)	9 Months Ended
	Sep. 30, 2023
Fair Value Disclosures [Abstract]
Fair value measurements	The Company measures its investments in certain fixed-income and equity securities at fair value with changes in fair value recognized in income.

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Income Taxes (Policies)	9 Months Ended
	Sep. 30, 2023
Income Tax Disclosure [Abstract]
Income Tax, Policy	Income tax expense is based on reported income before income taxes. Deferred income taxes reflect the tax effect of temporary differences between asset and liability amounts that are recognized for financial reporting purposes and the amounts that are recognized for income tax purposes. These deferred taxes are measured by applying currently enacted tax laws.Valuation allowances are recognized to reduce deferred tax assets to the amount that will more likely than not be realized. In assessing the need for a valuation allowance, management considers all available evidence for each jurisdiction including past operating results, estimates of future taxable income and the feasibility of ongoing tax planning strategies and actions. When there is a change in determination as to the amount of deferred tax assets that can be realized, the valuation allowance is adjusted with a corresponding impact to provision for income taxes in the period in which such determination is made.

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Business segment data (Policies)	9 Months Ended
	Sep. 30, 2023
Segment Reporting [Abstract]
Business segment data	The Company’s reportable segments are those that are based on the Company’s method of internal reporting and management of the business and are Pacific, Northwest, Mountain and North Central. The South and Energy Services operating segments do not meet the criteria to be reportable segments and, as such, are combined with its corporate services in All Other. Each segment is led by a segment president that reports to the Company’s chief operating officer. The chief operating officer works directly with the chief executive officer, the chief operating decision maker, to evaluate the performance of the segments using EBITDA and the allocation of resources.

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Contingencies (Policies)	9 Months Ended
	Sep. 30, 2023
Commitments and Contingencies Disclosure [Abstract]
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. The Company accrues 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. The Company does 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, the Company discloses 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.

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Receivables and allowance for expected credit losses (Tables)

9 Months Ended

Sep. 30, 2023

Credit Loss [Abstract]

Schedule of Accounts, Notes, Loans and Financing Receivable

Receivables were as follows:

	September 30, 2023		December 31, 2022
	(In thousands)
Trade receivables	$	236,373	$	104,347
Contract receivables	223,874		82,428
Retention receivables	37,814		28,859
Receivables, gross	498,061		215,634
Less expected credit loss	6,195		5,477
Receivables, net	$	491,866	$	210,157

Accounts Receivable, Allowance for Credit Loss

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

	Pacific		Northwest		Mountain		North Central		All Other		Total
	(In thousands)
At December 31, 2022	$	2,045	$	1,253	$	1,278	$	839	$	62	$	5,477
Current expected credit loss provision	45		313		164		(89)		(1)		432
Less write-offs charged against the allowance	1		68		18		—		—		87
At March 31, 2023	$	2,089	$	1,498	$	1,424	$	750	$	61	$	5,822
Current expected credit loss provision	9		74		631		(132)		1		583
Less write-offs charged against the allowance	18		512		3		—		2		535
At June 30, 2023	$	2,080	$	1,060	$	2,052	$	618	$	60	$	5,870
Current expected credit loss provision	46		242		(152)		215		20		371
Less write-offs charged against the allowance	26		4		13		3		—		46
At September 30, 2023	$	2,100	$	1,298	$	1,887	$	830	$	80	$	6,195

	Pacific		Northwest		Mountain		North Central		All Other		Total
	(In thousands)
At December 31, 2021	$	2,052	$	512	$	1,610	$	1,152	$	80	$	5,406
Current expected credit loss provision	1		(125)		(130)		6		(5)		(253)
Less write-offs charged against the allowance	1		20		3		1		1		26
At March 31, 2022	$	2,052	$	367	$	1,477	$	1,157	$	74	$	5,127
Current expected credit loss provision	11		58		(17)		(37)		(3)		12
Less write-offs charged against the allowance	—		56		4		47		2		109
At June 30, 2022	$	2,063	$	369	$	1,456	$	1,073	$	69	$	5,030
Current expected credit loss provision	(6)		194		(111)		(141)		9		(55)
Less write-offs charged against the allowance	9		7		40		4		16		76
At September 30, 2022	$	2,048	$	556	$	1,305	$	928	$	62	$	4,899

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Inventories (Tables)

9 Months Ended

Sep. 30, 2023

Inventory Disclosure [Abstract]

Inventories

Inventories on the Consolidated Balance Sheets were as follows:

	September 30, 2023		December 31, 2022
	(In thousands)
Finished products	$	213,702	$	211,496
Raw materials	63,156		78,571
Supplies and parts	37,853		33,210
Total	$	314,711	$	323,277

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Earnings per share (Tables)

9 Months Ended

Sep. 30, 2023

Earnings Per Share [Abstract]

Weighted average common shares outstanding

Basic and diluted earnings 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				Nine Months Ended
	September 30,				September 30,
	2023		2022		2023		2022
	(In thousands, except per share amounts)
Net income	$	146,655	$	99,657	$	162,171	$	98,210
Weighted average common shares outstanding - basic	56,566		56,566		56,566		56,566
Effect of dilutive restricted stock units	169		—		67		—
Weighted average common shares outstanding - diluted	56,735		56,566		56,633		56,566
Shares excluded from the calculation of diluted earnings per share	—		—		—		—
Net income per share - basic	$	2.59	$	1.76	$	2.87	$	1.74
Net income per share - diluted	$	2.58	$	1.76	$	2.86	$	1.74

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Accumulated other comprehensive loss (Tables)

9 Months Ended

Sep. 30, 2023

Equity [Abstract]

Accumulated 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)
At 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)
Other comprehensive loss before reclassification	—		—		—
Amounts reclassified from accumulated other comprehensive loss	—		49		49
Net current-period other comprehensive income	—		49		49
At September 30, 2023	$	—	$	(12,135)	$	(12,135)

	Net Unrealized Loss on Derivative  Instruments  Qualifying as Hedges		Postretirement  Liability Adjustment		Total Accumulated  Other Comprehensive  Loss
	(In thousands)
At December 31, 2021	$	(418)	$	(24,072)	$	(24,490)
Amounts reclassified from accumulated other comprehensive loss	82		221		303
Net current-period other comprehensive income	82		221		303
At March 31, 2022	$	(336)	$	(23,851)	$	(24,187)
Other comprehensive income before reclassification	—		5,820		5,820
Amounts reclassified from accumulated other comprehensive loss	82		220		302
Net current-period other comprehensive income	82		6,040		6,122
At June 30, 2022	$	(254)	$	(17,811)	$	(18,065)
Amounts reclassified from accumulated other comprehensive loss	82		221		303
Net current-period other comprehensive income	82		221		303
At September 30, 2022	$	(172)	$	(17,590)	$	(17,762)

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				Nine Months Ended				Location on Consolidated Statements of Operations
	September 30,				September 30,
	2023		2022		2023		2022
	(In thousands)
Reclassification adjustment for loss on derivative income	$	—	$	(109)	$	(118)	$	(326)	Interest expense
	—		27		28		80		Income taxes
	—		(82)		(90)		(246)
Amortization of postretirement liability losses included in net periodic benefit cost	(65)		(292)		(191)		(875)		Other income
	16		71		47		213		Income taxes
	(49)		(221)		(144)		(662)
Total reclassifications	$	(49)	$	(303)	$	(234)	$	(908)

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Revenue from contracts with customers (Tables)

9 Months Ended

Sep. 30, 2023

Revenue from Contract with Customer [Abstract]

Disaggregation of revenue

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. The Company believes 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 15.

Three Months Ended September 30, 2023	Pacific		Northwest		Mountain		North Central		All Other		Total
	(In thousands)
Aggregates	$	33,624	$	57,398	$	39,519	$	47,656	$	15,388	$	193,585
Ready-mix concrete	39,861		46,785		44,053		73,183		12,157		216,039
Asphalt	14,050		43,462		59,673		95,053		10,539		222,777
Other	81,081		4,497		11		10,211		118,312		214,112
Contracting services public-sector	32,632		68,316		135,700		181,779		23,483		441,910
Contracting services private-sector	17,745		25,144		43,944		8,526		46		95,405
Internal sales	(37,566)		(36,683)		(68,178)		(111,288)		(39,741)		(293,456)
Revenues from contracts with customers	$	181,427	$	208,919	$	254,722	$	305,120	$	140,184	$	1,090,372

Three Months Ended September 30, 2022	Pacific		Northwest		Mountain		North Central		All Other		Total
	(In thousands)
Aggregates	$	28,695	$	52,614	$	31,258	$	45,039	$	14,197	$	171,803
Ready-mix concrete	35,395		45,600		37,334		64,496		16,082		198,907
Asphalt	10,935		45,110		45,553		96,830		7,133		205,561
Other	63,002		4,447		12		8,711		90,539		166,711
Contracting services public-sector	30,529		78,664		100,298		184,266		18,874		412,631
Contracting services private-sector	14,512		20,424		38,755		5,664		221		79,576
Internal sales	(30,710)		(42,627)		(49,089)		(110,700)		(26,635)		(259,761)
Revenues from contracts with customers	$	152,358	$	204,232	$	204,121	$	294,306	$	120,411	$	975,428

Nine Months Ended September 30, 2023	Pacific		Northwest		Mountain		North Central		All Other		Total
	(In thousands)
Aggregates	$	79,768	$	147,937	$	78,051	$	81,999	$	35,767	$	423,522
Ready-mix concrete	106,531		125,273		92,929		139,369		33,604		497,706
Asphalt	21,640		84,908		89,955		141,942		22,888		361,333
Other	168,104		11,513		21		22,703		193,528		395,869
Contracting services public-sector	53,450		138,621		244,320		280,853		61,293		778,537
Contracting services private-sector	37,220		80,258		94,706		13,884		1,131		227,199
Internal sales	(75,345)		(84,937)		(108,888)		(167,055)		(64,479)		(500,704)
Revenues from contracts with customers	$	391,368	$	503,573	$	491,094	$	513,695	$	283,732	$	2,183,462

Nine Months Ended September 30, 2022	Pacific		Northwest		Mountain		North Central		All Other		Total
	(In thousands)
Aggregates	$	72,088	$	129,752	$	67,388	$	75,718	$	40,892	$	385,838
Ready-mix concrete	98,520		121,079		84,950		124,026		46,959		475,534
Asphalt	26,909		79,801		77,021		141,595		19,886		345,212
Other	143,140		11,804		26		20,766		152,757		328,493
Contracting services public-sector	63,450		141,783		202,495		275,797		52,933		736,458
Contracting services private-sector	38,922		60,321		91,783		8,809		863		200,698
Internal Sales	(76,911)		(84,733)		(90,654)		(162,342)		(60,386)		(475,026)
Revenues from contracts with customers	$	366,118	$	459,807	$	433,009	$	484,369	$	253,904	$	1,997,207

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Uncompleted contracts (Tables)

9 Months Ended

Sep. 30, 2023

Revenue from Contract with Customer [Abstract]

Contract balances

The changes in contract assets and liabilities were as follows:

	September 30, 2023		December 31, 2022		Change		Location on Consolidated Balance Sheets
	(In thousands)
Contract assets	$	50,545	$	31,145	$	19,400	Costs and estimated earnings in excess of billings on uncompleted contracts
Contract liabilities	(58,785)		(39,843)		(18,942)		Billings in excess of costs and estimated earnings on uncompleted contracts
Net contract liabilities	$	(8,240)	$	(8,698)	$	458

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Goodwill and other intangible assets (Tables)

9 Months Ended

Sep. 30, 2023

Goodwill and Intangible Assets Disclosure [Abstract]

Changes in the carrying amount of goodwill

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

	Balance at January 1, 2023		Goodwill Acquired During the Year		Measurement Period Adjustments		Balance at September 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
All Other	42,528		—		—		42,528
Total	$	274,540	$	—	$	(62)	$	274,478

Other amortizable intangible assets

Other amortizable intangible assets were as follows:

	September 30, 2023		December 31, 2022
	(In thousands)
Customer relationships	$	18,540	$	18,540
Less accumulated amortization	8,668		7,367
	9,872		11,173
Noncompete agreements	4,039		4,039
Less accumulated amortization	3,358		2,985
	681		1,054
Other	2,479		5,279
Less accumulated amortization	1,569		4,076
	910		1,203
Total	$	11,463	$	13,430

Estimated amortization expense

Estimated amortization expense for identifiable intangible assets as of September 30, 2023, was:

	Remainder of 2023		2024		2025		2026		2027		Thereafter
	(In thousands)
Amortization expense	$	590	$	2,157	$	2,042	$	1,739	$	1,717	$	3,218

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Fair value measurements (Tables)

9 Months Ended

Sep. 30, 2023

Fair Value Disclosures [Abstract]

Assets and liabilities measured at fair value on a recurring basis

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

	Fair Value Measurements at September 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 September 30, 2023
	(In thousands)
Assets:
Money market funds	$	—	$	3,199	$	—	$	3,199
Insurance contracts*	—		23,483		—		23,483
Total assets measured at fair value	$	—	$	26,682	$	—	$	26,682

*    The insurance contracts invest approximately 41 percent in fixed-income investments, 19 percent in cash equivalents, 18 percent in common stock of large-cap companies, 8 percent in common stock of mid-cap companies, 8 percent target date investments, 5 percent in common stock of small-cap companies and 1 percent in international investments.

	Fair Value Measurements at December 31, 2022, 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, 2022
	(In thousands)
Assets:
Money market funds	$	—	$	2,448	$	—	$	2,448
Insurance contracts*	—		20,083		—		20,083
Total assets measured at fair value	$	—	$	22,531	$	—	$	22,531

*    The insurance contracts invest approximately 63 percent in fixed-income investments, 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, 6 percent in target date investments and 2 percent in cash equivalents.

Fair Value, by Balance Sheet Grouping

The estimated fair value of the Company's Level 2 long-term debt was as follows:

	September 30, 2023
	(In thousands)
Carrying amount	$	698,747
Fair value	$	700,687

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Debt (Tables)

9 Months Ended

Sep. 30, 2023

Debt Disclosure [Abstract]

Long-term debt outstanding

Long-term debt outstanding was as follows:

	Weighted Average Interest Rate at September 30, 2023		September 30, 2023
			(In thousands)
Term loan agreement due on May 31, 2028	7.52	%	$	273,281
Senior notes due on May 1, 2031	7.75	%	425,000
Other notes due on January 1, 2061	—	%	466
Less unamortized debt issuance costs			16,016
Total long-term debt			682,731
Less current maturities			7,082
Net long-term debt			$	675,649

Schedule of debt maturities

Long-term debt maturities, which excludes unamortized debt issuance costs, at September 30, 2023, were as follows:

	Remainder of 2023		2024		2025		2026		2027		Thereafter
	(In thousands)
Long-term debt maturities	$	1,719	$	7,082	$	10,520	$	13,802	$	17,187	$	648,437

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Cash flow information (Tables)

9 Months Ended

Sep. 30, 2023

Supplemental Cash Flow Information [Abstract]

Cash expenditures for interest and income taxes and noncash investing and financing transactions

Cash expenditures for interest and income taxes were as follows:

	Nine Months Ended
	September 30,
	2023		2022
	(In thousands)
Interest paid, net	$	32,028	$	19,472
Income taxes paid, net	$	22,183	$	23,163

Noncash investing and financing transactions were as follows:

	Nine Months Ended
	September 30,
	2023		2022
	(In thousands)
Right-of-use assets obtained in exchange for new operating lease liabilities	$	9,717	$	5,851
Property, plant and equipment additions in accounts payable	$	2,832	$	4,884
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	$	—

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Business segment data (Tables)

9 Months Ended

Sep. 30, 2023

Segment Reporting [Abstract]

Information on the Company's businesses

Information on the Company's segments was as follows:

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2023		2022		2023		2022
	(In thousands)
External operating revenues:
Pacific	$	181,427	$	152,358	$	391,368	$	366,118
Northwest	208,919		204,232		503,573		459,807
Mountain	254,722		204,121		491,094		433,009
North Central	305,120		294,306		513,695		484,369
All Other	140,184		120,411		283,732		253,904
Total external operating revenues	$	1,090,372	$	975,428	$	2,183,462	$	1,997,207
Intersegment operating revenues:
Pacific	$	37,566	$	30,710	$	75,345	$	76,911
Northwest	36,683		42,627		84,937		84,733
Mountain	68,178		49,089		108,888		90,654
North Central	111,288		110,700		167,055		162,342
All Other	39,741		26,635		64,479		60,386
Total intersegment operating revenues	$	293,456	$	259,761	$	500,704	$	475,026
EBITDA:
Pacific	$	37,558	$	24,563	$	56,486	$	45,194
Northwest	48,867		43,797		102,711		79,774
Mountain	60,473		39,644		86,486		60,244
North Central	70,508		58,584		71,402		50,424
All Other	23,994		5,500		35,323		5,578
Total segment EBITDA	$	241,400	$	172,088	$	352,408	$	241,214

Reconciliation of Revenue from Segments to Consolidated

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

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2023		2022		2023		2022
	(In thousands)
Total reportable segment operating revenues	$	1,203,903	$	1,088,143	$	2,335,955	$	2,157,943
Other operating revenues	179,925		147,046		348,211		314,290
Less:
Elimination of intersegment operating revenues	293,456		259,761		500,704		475,026
Total consolidated operating revenues	$	1,090,372	$	975,428	$	2,183,462	$	1,997,207

Segment, Reconciliation of Other Items from Segments to Consolidated

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

	Three Months Ended				Nine Months Ended
	Sept. 30,				Sept. 30,
	2023		2022		2023		2022
	(In thousands)
Total EBITDA for reportable segments	$	217,406	$	166,588	$	317,085	$	235,636
Other EBITDA	23,994		5,500		35,323		5,578
Less:
Depreciation, depletion and amortization	31,752		30,450		92,511		88,551
Interest expense, net*	14,774		8,817		41,399		21,506
Total consolidated income before income taxes	$	194,874	$	132,821	$	218,498	$	131,157
*Interest, net is interest expense net of interest income.

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Employee benefit plans (Tables)

9 Months Ended

Sep. 30, 2023

Retirement Benefits [Abstract]

Schedule of net benefit costs

Components of net periodic benefit cost for the Company's pension benefit plans were as follows:

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2023		2022		2023		2022
	(In thousands)
Components of net periodic benefit cost:
Interest cost	$	408	$	282	$	1,224	$	846
Expected return on assets	(450)		(493)		(1,350)		(1,479)
Amortization of net actuarial loss	128		214		384		642
Net periodic benefit cost	$	86	$	3	$	258	$	9

Components of net periodic benefit cost for the Company's other postretirement benefit plans were as follows:

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2023		2022		2023		2022
	(In thousands)
Components of net periodic benefit cost:
Service cost	$	91	$	131	$	270	$	393
Interest cost	180		128		541		384
Expected return on assets	—		(3)		12		(9)
Amortization of prior service credit	(20)		(20)		(60)		(60)
Amortization of net actuarial (gain) loss	(43)		88		(132)		264
Net periodic benefit cost	$	208	$	324	$	631	$	972

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Background (Details)	May 31, 2023
Restructuring and Related Activities [Abstract]
Percent of Shares Distributed in Conjunction with Spinoff	90.00%
Percent of Shares, Retained by Parent, in Conjunction with Spinoff	10.00%

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Basis of presentation (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
	May 30, 2023	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Form 10 Separation Adjustments to Costs of Goods Sold			$ 4.4		$ (1.6)
Form 10 Separation Adjustments to Net Income			3.4		(1.2)
Costs and Expenses, Related Party		$ 0.0	$ 3.8	$ 8.7	$ 13.4
Related-party notes payable to Centennial	$ 889.7
Dividend paid from debt proceeds to Centennial	825.0
Net contribution from Centennial after repayment of notes	$ 64.7

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Basis of presentation (Details 2) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022	Sep. 30, 2022	Dec. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Cash, cash equivalents and restricted cash	$ 116,159	$ 10,090	$ 19,028	$ 13,848
Cash and cash equivalents	84,000
Restricted cash	$ 32,200		$ 0

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Receivables and allowance for expected credit losses (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Credit Loss [Abstract]
Accounts Receivable, Noncurrent, 90 Days or More Past Due, Still Accruing	$ 14.4	$ 11.2

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Receivables and allowance for expected credit losses (Details 2) - Trade Accounts Receivable - USD ($) $ in Thousands	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Trade receivables	$ 236,373			$ 104,347
Contract receivables	223,874			82,428
Retention receivables	37,814			28,859
Receivables, gross	498,061			215,634
Less expected credit loss	6,195	$ 5,870	$ 5,822	5,477	$ 4,899	$ 5,030	$ 5,127	$ 5,406
Receivables, net	$ 491,866			$ 210,157

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Receivables and allowance for expected credit losses (Details 3) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2023	Sep. 30, 2022
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Provision for credit losses							$ 1,386	$ (296)
Trade Accounts Receivable
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance	$ 5,870	$ 5,822	$ 5,477	$ 5,030	$ 5,127	$ 5,406	5,477	5,406
Provision for credit losses	371	583	432	(55)	12	(253)
Less write-offs charged against the allowance	46	535	87	76	109	26
Balance	6,195	5,870	5,822	4,899	5,030	5,127	6,195	4,899
Pacific | Trade Accounts Receivable
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance	2,080	2,089	2,045	2,063	2,052	2,052	2,045	2,052
Provision for credit losses	46	9	45	(6)	11	1
Less write-offs charged against the allowance	26	18	1	9	0	1
Balance	2,100	2,080	2,089	2,048	2,063	2,052	2,100	2,048
Northwest | Trade Accounts Receivable
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance	1,060	1,498	1,253	369	367	512	1,253	512
Provision for credit losses	242	74	313	194	58	(125)
Less write-offs charged against the allowance	4	512	68	7	56	20
Balance	1,298	1,060	1,498	556	369	367	1,298	556
Mountain | Trade Accounts Receivable
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance	2,052	1,424	1,278	1,456	1,477	1,610	1,278	1,610
Provision for credit losses	(152)	631	164	(111)	(17)	(130)
Less write-offs charged against the allowance	13	3	18	40	4	3
Balance	1,887	2,052	1,424	1,305	1,456	1,477	1,887	1,305
North Central | Trade Accounts Receivable
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance	618	750	839	1,073	1,157	1,152	839	1,152
Provision for credit losses	215	(132)	(89)	(141)	(37)	6
Less write-offs charged against the allowance	3	0	0	4	47	1
Balance	830	618	750	928	1,073	1,157	830	928
All Other | Trade Accounts Receivable
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance	60	61	62	69	74	80	62	80
Provision for credit losses	20	1	(1)	9	(3)	(5)
Less write-offs charged against the allowance	0	2	0	16	2	1
Balance	$ 80	$ 60	$ 61	$ 62	$ 69	$ 74	$ 80	$ 62

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Inventories (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Inventory Disclosure [Abstract]
Finished products	$ 213,702	$ 211,496
Raw materials	63,156	78,571
Supplies and parts	37,853	33,210
Total	$ 314,711	$ 323,277

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Earnings per share (Details 1) - shares	May 31, 2023	Dec. 31, 2022
Earnings Per Share [Abstract]
Common Stock, Shares, Issued	56,997,350	80,000
Treasury Stock, Common, Shares	(431,136)

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Earnings per share (Details 2) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2023	Sep. 30, 2022
Earnings Per Share [Abstract]
Net Income (Loss)	$ 146,655	$ 56,836	$ (41,320)	$ 99,657	$ 38,562	$ (40,010)	$ 162,171	$ 98,210
Weighted Average Number of Shares Outstanding, Basic	56,566			56,566			56,566	56,566
Effect of dilutive restricted stock units	169			0			67	0
Weighted average common shares outstanding - diluted	56,735			56,566			56,633	56,566
Shares excluded from the calculation of diluted earnings per share	0			0			0	0
Income per share, Basic, Total	$ 2.59			$ 1.76			$ 2.87	$ 1.74
Income per share, Diluted, Total	$ 2.58			$ 1.76			$ 2.86	$ 1.74

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Equity (Details) - USD ($) $ / shares in Units, $ in Thousands	Sep. 30, 2023	Jun. 30, 2023	May 31, 2023	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021
Class of Stock [Line Items]
Common Stock, Shares, Issued			56,997,350		80,000
Common Stock, Par or Stated Value Per Share	$ 0.01		$ 0.01		$ 10
MDU Resources Common Stock Held by Subsidiary at Cost, Shares			538,921		(538,921)
Treasury Stock, Common, Shares			431,136
Total stockholders' equity	$ 1,243,018	$ 1,094,852		$ 974,769	$ 1,028,589	$ 1,011,316	$ 923,988	$ 897,035	$ 952,844
MDU Resources' Common Stock Held by Subsidiary
Class of Stock [Line Items]
Total stockholders' equity	$ 3,600

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Accumulated other comprehensive loss (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2023	Sep. 30, 2022
Accumulated other comprehensive loss [Roll Forward]
Balance	$ 1,094,852	$ 974,769	$ 1,028,589	$ 923,988	$ 897,035	$ 952,844	$ 1,028,589	$ 952,844
Net current-period other comprehensive income	49	75	93	303	6,122	303	217	6,728
Balance	1,243,018	1,094,852	974,769	1,011,316	923,988	897,035	1,243,018	1,011,316
Net unrealized loss on derivative instruments qualifying as hedges
Accumulated other comprehensive loss [Roll Forward]
Balance	0	(44)	(90)	(254)	(336)	(418)	(90)	(418)
Amounts reclassified from accumulated other comprehensive loss	0	44	46	82	82	82
Other comprehensive income (loss) before reclassifications	0	0			0
Net current-period other comprehensive income	0	44	46	82	82	82
Balance	0	0	(44)	(172)	(254)	(336)	0	(172)
Postretirement liability adjustment
Accumulated other comprehensive loss [Roll Forward]
Balance	(12,184)	(12,215)	(12,262)	(17,811)	(23,851)	(24,072)	(12,262)	(24,072)
Amounts reclassified from accumulated other comprehensive loss	49	48	47	221	220	221
Other comprehensive income (loss) before reclassifications	0	(17)			5,820
Net current-period other comprehensive income	49	31	47	221	6,040	221
Balance	(12,135)	(12,184)	(12,215)	(17,590)	(17,811)	(23,851)	(12,135)	(17,590)
Total accumulated other comprehensive loss
Accumulated other comprehensive loss [Roll Forward]
Balance	(12,184)	(12,259)	(12,352)	(18,065)	(24,187)	(24,490)	(12,352)	(24,490)
Amounts reclassified from accumulated other comprehensive loss	49	92	93	303	302	303
Other comprehensive income (loss) before reclassifications	0	(17)			5,820
Net current-period other comprehensive income	49	75	93	303	6,122	303
Balance	$ (12,135)	$ (12,184)	$ (12,259)	$ (17,762)	$ (18,065)	$ (24,187)	$ (12,135)	$ (17,762)

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Reclassification out of accumulated other comprehensive loss (Details 2) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2023	Sep. 30, 2022
Reclassification adjustment out of accumulated other comprehensive loss [Line Items]
Interest expense	$ (15,354)			$ (8,817)			$ (44,005)	$ (21,506)
Income tax expense	(48,219)			(33,164)			(56,327)	(32,947)
Other income	7			(1,277)			3,311	(6,056)
Net Income (Loss)	146,655	$ 56,836	$ (41,320)	99,657	$ 38,562	$ (40,010)	162,171	98,210
Reclassification out of accumulated other comprehensive loss
Reclassification adjustment out of accumulated other comprehensive loss [Line Items]
Net Income (Loss)	(49)			(303)			(234)	(908)
Reclassification adjustment for loss on derivative income | Reclassification out of accumulated other comprehensive loss | Interest rate contract
Reclassification adjustment out of accumulated other comprehensive loss [Line Items]
Interest expense	0			(109)			(118)	(326)
Income tax expense	0			27			28	80
Net Income (Loss)	0			(82)			(90)	(246)
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 tax expense	16			71			47	213
Other income	(65)			(292)			(191)	(875)
Net Income (Loss)	$ (49)			$ (221)			$ (144)	$ (662)

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Disaggregation of revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Disaggregation of Revenue [Line Items]
Revenues	$ 1,090,372	$ 975,428	$ 2,183,462	$ 1,997,207
Aggregates
Disaggregation of Revenue [Line Items]
Revenues	193,585	171,803	423,522	385,838
Ready-mix concrete
Disaggregation of Revenue [Line Items]
Revenues	216,039	198,907	497,706	475,534
Asphalt
Disaggregation of Revenue [Line Items]
Revenues	222,777	205,561	361,333	345,212
Other
Disaggregation of Revenue [Line Items]
Revenues	214,112	166,711	395,869	328,493
Contracting services public-sector
Disaggregation of Revenue [Line Items]
Revenues	441,910	412,631	778,537	736,458
Contracting services private-sector
Disaggregation of Revenue [Line Items]
Revenues	95,405	79,576	227,199	200,698
Internal sales
Disaggregation of Revenue [Line Items]
Revenues	(293,456)	(259,761)	(500,704)	(475,026)
Pacific
Disaggregation of Revenue [Line Items]
Revenues	181,427	152,358	391,368	366,118
Pacific | Aggregates
Disaggregation of Revenue [Line Items]
Revenues	33,624	28,695	79,768	72,088
Pacific | Ready-mix concrete
Disaggregation of Revenue [Line Items]
Revenues	39,861	35,395	106,531	98,520
Pacific | Asphalt
Disaggregation of Revenue [Line Items]
Revenues	14,050	10,935	21,640	26,909
Pacific | Other
Disaggregation of Revenue [Line Items]
Revenues	81,081	63,002	168,104	143,140
Pacific | Contracting services public-sector
Disaggregation of Revenue [Line Items]
Revenues	32,632	30,529	53,450	63,450
Pacific | Contracting services private-sector
Disaggregation of Revenue [Line Items]
Revenues	17,745	14,512	37,220	38,922
Pacific | Internal sales
Disaggregation of Revenue [Line Items]
Revenues	(37,566)	(30,710)	(75,345)	(76,911)
Northwest
Disaggregation of Revenue [Line Items]
Revenues	208,919	204,232	503,573	459,807
Northwest | Aggregates
Disaggregation of Revenue [Line Items]
Revenues	57,398	52,614	147,937	129,752
Northwest | Ready-mix concrete
Disaggregation of Revenue [Line Items]
Revenues	46,785	45,600	125,273	121,079
Northwest | Asphalt
Disaggregation of Revenue [Line Items]
Revenues	43,462	45,110	84,908	79,801
Northwest | Other
Disaggregation of Revenue [Line Items]
Revenues	4,497	4,447	11,513	11,804
Northwest | Contracting services public-sector
Disaggregation of Revenue [Line Items]
Revenues	68,316	78,664	138,621	141,783
Northwest | Contracting services private-sector
Disaggregation of Revenue [Line Items]
Revenues	25,144	20,424	80,258	60,321
Northwest | Internal sales
Disaggregation of Revenue [Line Items]
Revenues	(36,683)	(42,627)	(84,937)	(84,733)
Mountain
Disaggregation of Revenue [Line Items]
Revenues	254,722	204,121	491,094	433,009
Mountain | Aggregates
Disaggregation of Revenue [Line Items]
Revenues	39,519	31,258	78,051	67,388
Mountain | Ready-mix concrete
Disaggregation of Revenue [Line Items]
Revenues	44,053	37,334	92,929	84,950
Mountain | Asphalt
Disaggregation of Revenue [Line Items]
Revenues	59,673	45,553	89,955	77,021
Mountain | Other
Disaggregation of Revenue [Line Items]
Revenues	11	12	21	26
Mountain | Contracting services public-sector
Disaggregation of Revenue [Line Items]
Revenues	135,700	100,298	244,320	202,495
Mountain | Contracting services private-sector
Disaggregation of Revenue [Line Items]
Revenues	43,944	38,755	94,706	91,783
Mountain | Internal sales
Disaggregation of Revenue [Line Items]
Revenues	(68,178)	(49,089)	(108,888)	(90,654)
North Central
Disaggregation of Revenue [Line Items]
Revenues	305,120	294,306	513,695	484,369
North Central | Aggregates
Disaggregation of Revenue [Line Items]
Revenues	47,656	45,039	81,999	75,718
North Central | Ready-mix concrete
Disaggregation of Revenue [Line Items]
Revenues	73,183	64,496	139,369	124,026
North Central | Asphalt
Disaggregation of Revenue [Line Items]
Revenues	95,053	96,830	141,942	141,595
North Central | Other
Disaggregation of Revenue [Line Items]
Revenues	10,211	8,711	22,703	20,766
North Central | Contracting services public-sector
Disaggregation of Revenue [Line Items]
Revenues	181,779	184,266	280,853	275,797
North Central | Contracting services private-sector
Disaggregation of Revenue [Line Items]
Revenues	8,526	5,664	13,884	8,809
North Central | Internal sales
Disaggregation of Revenue [Line Items]
Revenues	(111,288)	(110,700)	(167,055)	(162,342)
All Other
Disaggregation of Revenue [Line Items]
Revenues	140,184	120,411	283,732	253,904
All Other | Aggregates
Disaggregation of Revenue [Line Items]
Revenues	15,388	14,197	35,767	40,892
All Other | Ready-mix concrete
Disaggregation of Revenue [Line Items]
Revenues	12,157	16,082	33,604	46,959
All Other | Asphalt
Disaggregation of Revenue [Line Items]
Revenues	10,539	7,133	22,888	19,886
All Other | Other
Disaggregation of Revenue [Line Items]
Revenues	118,312	90,539	193,528	152,757
All Other | Contracting services public-sector
Disaggregation of Revenue [Line Items]
Revenues	23,483	18,874	61,293	52,933
All Other | Contracting services private-sector
Disaggregation of Revenue [Line Items]
Revenues	46	221	1,131	863
All Other | Internal sales
Disaggregation of Revenue [Line Items]
Revenues	$ (39,741)	$ (26,635)	$ (64,479)	$ (60,386)

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Contract Balances (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Revenue from Contract with Customer [Abstract]
Contract assets	$ 50,545		$ 50,545		$ 31,145
Change in contract assets			19,400
Contract liabilities	(58,785)		(58,785)		(39,843)
Contract with Customer, Liability, Current Change			(18,942)
Net contract liabilities	(8,240)		(8,240)		$ (8,698)
Change in net contract assets (liabilities)			458
Amounts included in contract liability at the beginning of the period	3,400	$ 3,000	35,100	$ 29,200
Contract with customer, performance obligation satisfied in previous period	$ 12,100	$ 4,900	$ 10,600	$ 10,400

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Uncompleted contracts remaining performance obligations (Details 2) $ in Millions	Sep. 30, 2023 USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 732.2
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 677.7
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	12 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 38.5
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	13 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 16.0
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	25 months

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Goodwill rollforward (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2023 USD ($)
Goodwill [Roll Forward]
Balance at beginning of period	$ 274,540
Goodwill acquired during the year	0
Measurement period adjustments	(62)
Balance at end of period	274,478
Pacific
Goodwill [Roll Forward]
Balance at beginning of period	38,339
Goodwill acquired during the year	0
Measurement period adjustments	(62)
Balance at end of period	38,277
Northwest
Goodwill [Roll Forward]
Balance at beginning of period	90,978
Goodwill acquired during the year	0
Measurement period adjustments	0
Balance at end of period	90,978
Mountain
Goodwill [Roll Forward]
Balance at beginning of period	26,816
Goodwill acquired during the year	0
Measurement period adjustments	0
Balance at end of period	26,816
North Central
Goodwill [Roll Forward]
Balance at beginning of period	75,879
Goodwill acquired during the year	0
Measurement period adjustments	0
Balance at end of period	75,879
All Other
Goodwill [Roll Forward]
Balance at beginning of period	42,528
Goodwill acquired during the year	0
Measurement period adjustments	0
Balance at end of period	$ 42,528

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Other intangible assets (Details 2) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Finite-Lived Intangible Assets [Line Items]
Intangible assets, net (excluding goodwill)	$ 11,463,000		$ 11,463,000		$ 13,430,000
Amortization of intangible assets	647,000	$ 729,000	2,000,000	$ 2,100,000
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	18,540,000		18,540,000		18,540,000
Intangible assets, less accumulated amortization	8,668,000		8,668,000		7,367,000
Intangible assets, net (excluding goodwill)	9,872,000		9,872,000		11,173,000
Noncompete agreements
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	4,039,000		4,039,000		4,039,000
Intangible assets, less accumulated amortization	3,358,000		3,358,000		2,985,000
Intangible assets, net (excluding goodwill)	681,000		681,000		1,054,000
Other intangible assets
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	2,479,000		2,479,000		5,279,000
Intangible assets, less accumulated amortization	1,569,000		1,569,000		4,076,000
Intangible assets, net (excluding goodwill)	$ 910,000		$ 910,000		$ 1,203,000

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Future amortization expense (Details 3) $ in Thousands	Sep. 30, 2023 USD ($)
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Remainder of 2023	$ 590
2024	2,157
2025	2,042
2026	1,739
2027	1,717
Thereafter	$ 3,218

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Fair value measurements insurance contracts (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Fair Value Disclosures [Abstract]
Investments used to satisfy nonqualified benefit plans obligations	$ 23,500,000		$ 23,500,000		$ 20,100,000
Net unrealized gain (loss) on investments used to satisfy obligations under nonqualified benefit plans	(597,000)	$ (541,000)	685,000	$ (3,200,000)
Proceeds from Retired Contracts as part of the Separation	$ 4,800,000		$ 4,800,000

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Fair value measurements (Details 2) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Concentration risks, percentage [Abstract]
Percentage in fixed-income and other investments	41.00%	63.00%
Percentage investment in cash and cash equivalents	19.00%	2.00%
Percentage investment in common stock of large-cap companies	18.00%	15.00%
Percentage investment in common stock of mid-cap companies	8.00%	8.00%
Percentage investment in target date investments	8.00%	6.00%
Percentage investment in common stock of small-cap companies	5.00%	6.00%
Percentage investment in international investments	1.00%
Fair value, measurements, recurring
Fair value measurements [Line Items]
Assets, fair value disclosure	$ 26,682	$ 22,531
Fair value, inputs, level 2 | Fair value, measurements, recurring
Fair value measurements [Line Items]
Assets, fair value disclosure	26,682	22,531
Money market funds | Fair value, measurements, recurring
Fair value measurements [Line Items]
Assets, fair value disclosure	3,199	2,448
Money market funds | Fair value, inputs, level 2 | Fair value, measurements, recurring
Fair value measurements [Line Items]
Assets, fair value disclosure	3,199	2,448
Insurance contracts* | Fair value, measurements, recurring
Fair value measurements [Line Items]
Assets, fair value disclosure	23,483	20,083
Insurance contracts* | Fair value, inputs, level 2 | Fair value, measurements, recurring
Fair value measurements [Line Items]
Assets, fair value disclosure	$ 23,483	$ 20,083

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Fair value measures and disclosures (Details 3) $ in Thousands	Sep. 30, 2023 USD ($)
Fair value, balance sheet grouping [Line Items]
Long-term debt	$ 682,731
Reported Value Measurement [Member]
Fair value, balance sheet grouping [Line Items]
Long-term debt	698,747
Estimate of Fair Value Measurement [Member]
Fair value, balance sheet grouping [Line Items]
Long-term debt, fair value	$ 700,687

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Long-term debt outstanding (Details 1) - USD ($) $ in Thousands		9 Months Ended
	May 31, 2023	Sep. 30, 2023	Apr. 25, 2023	Dec. 31, 2022
Long-term debt outstanding [Line Items]
Long-term debt		$ 682,731
Mandatory Annual Amortization, Years One and Two		2.50%
Mandatory Annual Amortization, Years Three and Four		5.00%
Mandatory Annual Amortization, Years Five and Thereafter		7.50%
Maximum Distributions To The Company As A Ratio Of Average Consolidated Indebtedness To Consolidated EBITDA		4.75%
Minimum Interest Coverage To The Company As A Ratio Of Average Interest Expense To Consolidated EBITDA		2.25%
Long-term debt - current portion		$ 7,082		$ 211
Long-Term Debt, Excluding Current Maturities		675,649		$ 427
Senior Notes
Long-term debt outstanding [Line Items]
Long-term debt		$ 425,000	$ 425,000
Long-Term Debt, Percentage Bearing Fixed Interest, Percentage Rate			7.75%
Weighted Average Interest Rate		7.75%
Loans Payable
Long-term debt outstanding [Line Items]
Long-term debt	$ 275,000	$ 273,281
Weighted Average Interest Rate		7.52%
Revolving Credit Facility
Long-term debt outstanding [Line Items]
Long-term debt	350,000
Draw Down on Revolver	$ 190,000
Other Notes
Long-term debt outstanding [Line Items]
Long-term debt		$ 466
Weighted Average Interest Rate		0.00%
Long-term Debt
Long-term debt outstanding [Line Items]
Unamortized Debt Issuance Costs		$ 16,016

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Schedule of debt maturities (Details 2) $ in Thousands	Sep. 30, 2023 USD ($)
Long-term debt maturities [Line Items]
Remainder of 2023	$ 1,719
2024	7,082
2025	10,520
2026	13,802
2027	17,187
Thereafter	$ 648,437

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Cash flow information (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Supplemental Cash Flow Information [Abstract]
Interest paid, net	$ 32,028	$ 19,472
Income taxes paid, net	22,183	23,163
Right-of-use assets obtained in exchange for new operating lease liabilities	9,717	5,851
Property, plant and equipment additions in accounts payable	2,832	4,884
Equity contribution from Centennial related to the Separation	64,724	0
Equity contribution to MDU Resources for asset/liability transfers related to the Separation	(1,548)	0
MDU Resources' stock issued prior to spin in connection with a business combination	$ 383	$ 0

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Business segment data (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Segment Reporting Information [Line Items]
Revenues	$ 1,090,372	$ 975,428	$ 2,183,462	$ 1,997,207
EBITDA:	241,400	172,088	352,408	241,214
Pacific
Segment Reporting Information [Line Items]
Revenues	181,427	152,358	391,368	366,118
EBITDA:	37,558	24,563	56,486	45,194
Northwest
Segment Reporting Information [Line Items]
Revenues	208,919	204,232	503,573	459,807
EBITDA:	48,867	43,797	102,711	79,774
Mountain
Segment Reporting Information [Line Items]
Revenues	254,722	204,121	491,094	433,009
EBITDA:	60,473	39,644	86,486	60,244
North Central
Segment Reporting Information [Line Items]
Revenues	305,120	294,306	513,695	484,369
EBITDA:	70,508	58,584	71,402	50,424
All Other
Segment Reporting Information [Line Items]
Revenues	140,184	120,411	283,732	253,904
EBITDA:	23,994	5,500	35,323	5,578
Intersegment eliminations | Pacific
Segment Reporting Information [Line Items]
Revenues	37,566	30,710	75,345	76,911
Intersegment eliminations | Northwest
Segment Reporting Information [Line Items]
Revenues	36,683	42,627	84,937	84,733
Intersegment eliminations | Mountain
Segment Reporting Information [Line Items]
Revenues	68,178	49,089	108,888	90,654
Intersegment eliminations | North Central
Segment Reporting Information [Line Items]
Revenues	111,288	110,700	167,055	162,342
Intersegment eliminations | All Other
Segment Reporting Information [Line Items]
Revenues	39,741	26,635	64,479	60,386
Total intersegment operating revenues | Parent Company
Segment Reporting Information [Line Items]
Revenues	$ 293,456	$ 259,761	$ 500,704	$ 475,026

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Business segment data operating revenues reconciliation (Details 2) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ 1,090,372	$ 975,428	$ 2,183,462	$ 1,997,207
Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	1,203,903	1,088,143	2,335,955	2,157,943
Corporate, Non-Segment
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	179,925	147,046	348,211	314,290
Elimination of intersegment operating revenues | Parent Company
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ 293,456	$ 259,761	$ 500,704	$ 475,026

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Business segment data EBITDA reconciliation (Details 3) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Segment, Reconciliation of Other Items from Segments to Consolidated [Line Items]
EBITDA:	$ 241,400	$ 172,088	$ 352,408	$ 241,214
Depreciation, depletion and amortization	31,752	30,450	92,511	88,551
Interest expense, net	14,774	8,817	41,399	21,506
Total consolidated income before income taxes	194,874	132,821	218,498	131,157
Operating Segments
Segment, Reconciliation of Other Items from Segments to Consolidated [Line Items]
EBITDA:	217,406	166,588	317,085	235,636
Corporate, Non-Segment
Segment, Reconciliation of Other Items from Segments to Consolidated [Line Items]
EBITDA:	$ 23,994	$ 5,500	$ 35,323	$ 5,578

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Employee benefit plans (Details) $ in Millions	Jun. 01, 2023 USD ($)
Qualified plan | Unfunded plan | Other postretirement benefits
Defined benefit plan disclosure, net periodic benefit cost [Line Items]
Defined Benefit Plan, Benefit Obligation Transferred in Connection with Spinoff	$ 1.5

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Employee benefit plans (Details 2) - Qualified plan - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Underfunded plan | Pension benefits
Defined benefit plan disclosure, net periodic benefit cost [Line Items]
Interest cost	$ 408	$ 282	$ 1,224	$ 846
Expected return on assets	(450)	(493)	(1,350)	(1,479)
Amortization of net actuarial (gain) loss	128	214	384	642
Net periodic benefit cost	86	3	258	9
Unfunded plan | Other postretirement benefits
Defined benefit plan disclosure, net periodic benefit cost [Line Items]
Service cost	91	131	270	393
Interest cost	180	128	541	384
Expected return on assets	0	(3)	12	(9)
Amortization of prior service credit	(20)	(20)	(60)	(60)
Amortization of net actuarial (gain) loss	(43)	88	(132)	264
Net periodic benefit cost	$ 208	$ 324	$ 631	$ 972

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Litigation (Details) - USD ($)	Sep. 30, 2023	Dec. 31, 2022
Loss Contingencies [Line Items]
Potential liabilities related to litigation and environmental matters	$ 645,000	$ 1,000,000
Insurance Receivable		$ 325,000

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Guarantees (Details 2)	Sep. 30, 2023 USD ($)
Guarantor Obligations [Line Items]
Guarantor obligations, maximum exposure, undiscounted	$ 11,500,000
Amount outstanding under guarantees that is reflected on balance sheet	0
Letters of credit	4,800,000
Letters of credit set to expire - 2023	4,000,000
Letters of credit set to expire - 2024	771,000
Outstanding letters of credit	0
Amount of surety bonds outstanding	$ 619,200,000

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Related Party Disclosures (Details 1) - USD ($)	3 Months Ended	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2023
Related Party Transactions [Abstract]
Transition Services Agreement Payable	$ 1,300,000	$ 1,900,000
Transition Services Agreement Receivable	$ 407,000	$ 684,000

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Related Party Disclosures (Details 2) - USD ($) $ in Thousands	May 31, 2023	May 30, 2023	Sep. 30, 2023	Apr. 25, 2023
Related Party Transaction [Line Items]
Related-party notes payable to Centennial		$ 889,700
Long-term debt			$ 682,731
Dividend paid from debt proceeds to Centennial		825,000
Net contribution from Centennial after repayment of notes		$ 64,700
Senior Notes
Related Party Transaction [Line Items]
Long-term debt			425,000	$ 425,000
Long-Term Debt, Percentage Bearing Fixed Interest, Percentage Rate				7.75%
Loans Payable
Related Party Transaction [Line Items]
Long-term debt	$ 275,000		$ 273,281
Revolving Credit Facility
Related Party Transaction [Line Items]
Long-term debt	350,000
Draw Down on Revolver	$ 190,000