Consolidated Statements of Equity - USD ($) $ in Thousands	Total	Common Stock	Other Paid-in Capital	Retained Earnings	Total Accumulated Other Comprehensive Loss	Treasury Stock
Common stock, beginning balance (in shares) at Dec. 31, 2021		203,889,661
Beginning balance at Dec. 31, 2021	$ 3,382,874	$ 203,889	$ 1,461,205	$ 1,762,410	$ (41,004)	$ (3,626)
Treasury stock, common, beginning balance (in shares) at Dec. 31, 2021						(538,921)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	367,489			367,489
Other comprehensive income (loss)	10,421				10,421
Dividends declared on common stock	(178,761)			(178,761)
Employee stock-based compensation	10,254		10,254
Repurchase of common stock (in shares)						(266,821)
Repurchase of common stock	(7,399)					$ (7,399)
Issuance of common stock upon vesting of stock-based compensation, net of shares used for tax withholdings (in shares)						266,821
Issuance of common stock upon vesting of stock-based compensation, net of shares used for tax withholdings	(4,904)		(12,303)			$ 7,399
Issuance of common stock (in shares)		273,153
Issuance of common stock	7,155	$ 274	6,881
Common stock, ending balance (in shares) at Dec. 31, 2022		204,162,814
Ending balance at Dec. 31, 2022	3,587,129	$ 204,163	1,466,037	1,951,138	(30,583)	$ (3,626)
Treasury stock, common, ending balance (in shares) at Dec. 31, 2022						(538,921)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	414,707			414,707
Other comprehensive income (loss)	(107)				(107)
Dividends declared on common stock	(142,033)			(142,033)
Employee stock-based compensation	6,781		6,781
Repurchase of common stock (in shares)						(153,622)
Repurchase of common stock	(4,811)					$ (4,811)
Issuance of common stock upon vesting of stock-based compensation, net of shares used for tax withholdings (in shares)						153,622
Issuance of common stock upon vesting of stock-based compensation, net of shares used for tax withholdings	(3,040)		(7,851)			$ 4,811
Separation of Knife River and Everus (in shares)		(538,921)				(538,921)
Separation of Knife River and Everus	(954,726)	$ (539)		(970,119)	12,306	$ 3,626
Issuance of common stock (in shares)		65,197
Issuance of common stock	$ 1,333	$ 65	1,268
Common stock, ending balance (in shares) at Dec. 31, 2023	203,689,090	203,689,090
Ending balance at Dec. 31, 2023	$ 2,905,233	$ 203,689	1,466,235	1,253,693	(18,384)	$ 0
Treasury stock, common, ending balance (in shares) at Dec. 31, 2023						0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	281,108			281,108
Other comprehensive income (loss)	1,586				1,586
Dividends declared on common stock	(104,786)			(104,786)
Employee stock-based compensation	9,572		9,572
Issuance of common stock upon vesting of stock-based compensation, net of shares used for tax withholdings (in shares)		199,147
Issuance of common stock upon vesting of stock-based compensation, net of shares used for tax withholdings	(2,623)	$ 199	(2,822)
Separation of Knife River and Everus	(400,316)			(400,316)
Issuance of common stock (in shares)		46,341
Issuance of common stock	$ 800	$ 47	753
Common stock, ending balance (in shares) at Dec. 31, 2024	203,934,578	203,934,578
Ending balance at Dec. 31, 2024	$ 2,690,574	$ 203,935	$ 1,473,738	$ 1,029,699	$ (16,798)	$ 0
Treasury stock, common, ending balance (in shares) at Dec. 31, 2024						0