CONDENSED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
CONDENSED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) [Abstract]
Net earnings (loss)	$ (346,963)	$ 44,457
Other comprehensive income (loss), net of taxes:
Pension and postretirement benefits	82	411
Foreign currency translation adjustments	(1,274)	129
Total other comprehensive income (loss), net of taxes	(1,192)	540
Total comprehensive income (loss), net of taxes	(348,155)	44,997
Net earnings attributable to noncontrolling interests	(278)	(161)
Comprehensive income (loss) attributable to Kirby	$ (348,433)	$ 44,836