Consolidated Statements of Equity - USD ($) $ in Thousands	Total	Knife River Corporation Discontinued Operations, Disposed of by Means Other than Sale, Spinoff	Common Stock	Common Stock Knife River Corporation Discontinued Operations, Disposed of by Means Other than Sale, Spinoff	Other Paid-in Capital	Retained Earnings	Retained Earnings Knife River Corporation Discontinued Operations, Disposed of by Means Other than Sale, Spinoff	Total Accumulated Other Comprehensive Loss	Total Accumulated Other Comprehensive Loss Knife River Corporation Discontinued Operations, Disposed of by Means Other than Sale, Spinoff	Treasury Stock	Treasury Stock Knife River Corporation Discontinued Operations, Disposed of by Means Other than Sale, Spinoff
Common stock, beginning balance (in shares) at Dec. 31, 2020			201,061,198
Beginning balance at Dec. 31, 2020	$ 3,079,105		$ 201,061		$ 1,371,385	$ 1,558,363		$ (48,078)		$ (3,626)
Treasury stock, common, beginning balance (in shares) at Dec. 31, 2020										(538,921)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	378,131					378,131
Other comprehensive income (loss)	7,074							7,074
Dividends declared on common stock	(174,084)					(174,084)
Employee stock-based compensation	14,709				14,709
Repurchase of common stock (in shares)										(392,294)
Repurchase of common stock	(6,701)									$ (6,701)
Issuance of common stock upon vesting of stock-based compensation, net of shares used for tax withholdings	(4,127)				(10,828)					$ 6,701
Issuance of common stock upon vesting of stock-based compensation, net of shares used for tax withholdings (in shares)										392,294
Issuance of common stock (in shares)			2,828,463
Issuance of common stock	88,767		$ 2,828		85,939
Common stock, ending balance (in shares) at Dec. 31, 2021			203,889,661
Ending balance at Dec. 31, 2021	3,382,874		$ 203,889		1,461,205	1,762,410		(41,004)		$ (3,626)
Treasury stock, common, ending 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	(4,904)				(12,303)					$ 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 (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		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)									(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	(3,040)				(7,851)					$ 4,811
Issuance of common stock upon vesting of stock-based compensation, net of shares used for tax withholdings (in shares)										153,622
Separation of Knife River (in shares)				538,921							538,921
Separation of Knife River		$ (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