CONDENSED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
CONDENSED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) [Abstract]
Net earnings	$ 57,111	$ 77,213	$ 176,898	$ 216,135
Other comprehensive income (loss), net of taxes:
Pension and postretirement benefits	1,074	11	4,640	479
Foreign currency translation adjustments	49	(16)	81	(24)
Change in fair value of derivative instruments	0	0	0	84
Total other comprehensive income (loss), net of taxes	1,123	(5)	4,721	539
Total comprehensive income, net of taxes	58,234	77,208	181,619	216,674
Net earnings attributable to noncontrolling interests	(268)	(496)	(902)	(2,180)
Comprehensive income attributable to Kirby	$ 57,966	$ 76,712	$ 180,717	$ 214,494