CONDENSED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
CONDENSED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) [Abstract]
Net earnings	$ 77,213	$ 69,696	$ 216,135	$ 191,040
Other comprehensive income (loss), net of taxes:
Pension and postretirement benefits	11	1,185	479	2,856
Foreign currency translation adjustments	(16)	(124)	(24)	125
Change in fair value of derivative instruments	0	(12)	84	958
Total other comprehensive income (loss), net of taxes	(5)	1,049	539	3,939
Total comprehensive income, net of taxes	77,208	70,745	216,674	194,979
Net earnings attributable to noncontrolling interests	(496)	(573)	(2,180)	(2,246)
Comprehensive income attributable to Kirby	$ 76,712	$ 70,172	$ 214,494	$ 192,733