CONDENSED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Statement of Comprehensive Income [Abstract]
Net earnings	$ 28,606	$ 10,352	$ 46,192	$ 7,232
Other comprehensive income, net of taxes:
Pension and postretirement benefits	4,131	3,607	4,144	4,352
Foreign currency translation adjustments	(611)	(86)	(135)	(583)
Total other comprehensive income, net of taxes	3,520	3,521	4,009	3,769
Total comprehensive income, net of taxes	32,126	13,873	50,201	11,001
Net earnings attributable to noncontrolling interests	(149)	(162)	(301)	(417)
Comprehensive income attributable to Kirby	$ 31,977	$ 13,711	$ 49,900	$ 10,584