CONDENSED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
CONDENSED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) [Abstract]
Net earnings	$ 32,353	$ 57,111	$ 109,946	$ 176,898
Other comprehensive income (loss), net of taxes:
Pension and postretirement benefits	735	1,074	(1,765)	4,640
Foreign currency translation adjustments	0	49	0	81
Total other comprehensive income (loss), net of taxes	735	1,123	(1,765)	4,721
Total comprehensive income, net of taxes	33,088	58,234	108,181	181,619
Net earnings attributable to noncontrolling interests	(343)	(268)	(895)	(902)
Comprehensive income attributable to Kirby	$ 32,745	$ 57,966	$ 107,286	$ 180,717