CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Statement of Comprehensive Income [Abstract]
Net earnings (loss)	$ 222,905	$ 122,761	$ (246,771)
Other comprehensive income , net of taxes:
Pension and postretirement benefits	16,728	43,868	36,547
Foreign currency translation adjustments	1,425	(1,049)	(1,061)
Total other comprehensive income , net of taxes	18,153	42,819	35,486
Total comprehensive income (loss), net of taxes	241,058	165,580	(211,285)
Net (earnings) loss attributable to noncontrolling interests	30	(470)	(183)
Comprehensive income (loss) attributable to Kirby	$ 241,088	$ 165,110	$ (211,468)