CONDENSED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
CONDENSED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) [Abstract]
Net earnings	$ 58,376	$ 75,911	$ 119,787	$ 138,922
Other comprehensive income (loss), net of taxes:
Pension and postretirement benefits	2,458	444	3,566	468
Foreign currency translation adjustments	129	9	32	(8)
Change in fair value of derivative instruments	0	0	0	84
Total comprehensive income, net of taxes	2,587	453	3,598	544
Total comprehensive income, net of taxes	60,963	76,364	123,385	139,466
Net earnings attributable to noncontrolling interests	(301)	(919)	(634)	(1,684)
Comprehensive income attributable to Kirby	$ 60,662	$ 75,445	$ 122,751	$ 137,782