CONDENSED STATEMENTS OF EARNINGS (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Revenues:
Total revenues	$ 741,688	$ 491,705
Costs and expenses:
Costs of sales and operating expenses	553,317	344,799
Selling, general and administrative	76,796	46,142
Taxes, other than on income	8,535	6,649
Depreciation and amortization	54,218	48,170
Gain on disposition of assets	(1,898)	(99)
Total costs and expenses	690,968	445,661
Operating income	50,720	46,044
Other income (expense)	1,591	(589)
Interest expense	(9,780)	(4,457)
Earnings before taxes on income	42,531	40,998
Provision for taxes on income	(9,865)	(13,353)
Net earnings	32,666	27,645
Less: Net earnings attributable to noncontrolling interests	(195)	(162)
Net earnings attributable to Kirby	$ 32,471	$ 27,483
Net earnings per share attributable to Kirby common stockholders:
Basic (in dollars per share)	$ 0.54	$ 0.51
Diluted (in dollars per share)	$ 0.54	$ 0.51
Marine Transportation [Member]
Revenues:
Total revenues	$ 340,403	$ 343,652
Distribution and Services [Member]
Revenues:
Total revenues	$ 401,285	$ 148,053