Discontinued Operations - Schedule of Income and Expense Constituting Pretax Income From Discontinued Operations (Details) - Knife River Corporation - Discontinued Operations, Disposed of by Means Other than Sale, Spinoff - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Operating revenues	$ 2,377,332	$ 3,589,251	$ 5,226,766
Operating expenses	2,241,162	3,422,393	4,853,408
Operating (loss) income	136,170	166,858	373,358
Other income (expense)	12,446	10,599	4,119
Interest expense	7,118	47,229	38,590
Income from discontinued operations before income taxes	141,498	130,228	338,887
Income taxes	41,463	45,638	88,650
Discontinued operations, net of tax	$ 100,035	$ 84,590	$ 250,237