CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME [Abstract]
Net earnings	$ 284,608		$ 256,299		$ 212,619
Other comprehensive income (loss), net of taxes:
Pension and postretirement benefits	(44,294)		43,274		(10,270)
Foreign currency translation adjustments	(35)		108		102
Change in fair value of derivative instruments	85		952		5,217
Total other comprehensive income (loss), net of taxes	(44,244)	[1]	44,334	[1]	(4,951)	[1]
Total comprehensive income, net of taxes	240,364		300,633		207,668
Net earnings attributable to noncontrolling interests	(2,602)		(3,238)		(3,181)
Comprehensive income attributable to Kirby	$ 237,762		$ 297,395		$ 204,487

[1] (b) Reclassifications to net earnings of derivatives qualifying as effective hedges are recognized in interest expense or costs of sales and operating expenses as appropriate. (See Note 4 Derivative Instruments)