Stock-Based Compensation	9 Months Ended
	Sep. 30, 2023
Share-Based Payment Arrangement [Abstract]
Stock Based Compensation	Stock-based compensationIn connection with the completed separation of Knife River through the spinoff, the provisions of the existing compensation plans required adjustments to the number and terms of outstanding employee time-vested restricted stock units and performance share awards to preserve the intrinsic value of the awards immediately prior to the separation. The outstanding awards will continue to vest over the original vesting period, which is generally three years from the grant date. However, the performance share awards will no longer be subject to performance-based vesting conditions. The number of performance share awards were first adjusted for performance. The combined performance factors were determined based on the performance of the Company as of December 31, 2022. Outstanding awards at the time of the spinoff were converted into awards of the holder’s employer following separation. The Company recorded $204,000 of incremental compensation expense related to the conversion of the restricted stock units, which is being recognized over the remaining service period of one to three years. There was no incremental compensation expense related to the conversion of the performance share awards.