CONDENSED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Statement of Comprehensive Income [Abstract]
Net earnings	$ 40,621	$ 17,586
Other comprehensive income, net of taxes:
Pension and postretirement benefits	(61)	13
Foreign currency translation adjustments	225	476
Total other comprehensive income, net of taxes	164	489
Total comprehensive income, net of taxes	40,785	18,075
Net (earnings) loss attributable to noncontrolling interests	77	(152)
Comprehensive income attributable to Kirby	$ 40,862	$ 17,923