Subsequent Events (Details 2) - USD ($) $ in Thousands	Apr. 25, 2023	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2022
Long-term debt outstanding [Line Items]
Long-term debt		$ 2,847,068	$ 2,841,425	$ 2,747,763
Senior Notes
Long-term debt outstanding [Line Items]
Long-term debt		$ 2,258,500	$ 2,258,500	$ 2,275,000
Senior Notes | Subsequent Event [Member] | Knife River Holding Company
Long-term debt outstanding [Line Items]
Long-term debt	$ 425,000
Long-Term Debt, Percentage Bearing Fixed Interest, Percentage Rate	7.75%