CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME [Abstract]
Net earnings	$ 79,078	$ 313,903	$ 142,804
Other comprehensive income (loss), net of taxes:
Pension and postretirement benefits	7,638	18,748	(6,321)
Foreign currency translation adjustments	(819)	(146)	0
Reclassification to retained earnings of stranded tax effects from tax reform	(7,925)	0	0
Total other comprehensive income (loss), net of taxes	(1,106)	18,602	(6,321)
Total comprehensive income, net of taxes	77,972	332,505	136,483
Net earnings attributable to noncontrolling interests	(626)	(716)	(1,398)
Comprehensive income attributable to Kirby	$ 77,346	$ 331,789	$ 135,085