CONDENSED STATEMENTS OF EARNINGS (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenues:
Total revenues	$ 802,671	$ 473,328	$ 1,544,359	$ 965,033
Costs and expenses:
Costs of sales and operating expenses	588,628	324,750	1,141,945	669,549
Selling, general and administrative	92,588	46,550	169,384	92,692
Taxes, other than on income	10,552	6,344	19,087	12,993
Depreciation and amortization	55,492	48,293	109,710	96,463
Loss (gain) on disposition of assets	(442)	139	(2,340)	40
Total costs and expenses	746,818	426,076	1,437,786	871,737
Operating income	55,853	47,252	106,573	93,296
Other income (expense)	1,541	228	3,132	(361)
Interest expense	(12,540)	(4,465)	(22,320)	(8,922)
Earnings before taxes on income	44,854	43,015	87,385	84,013
Provision for taxes on income	(16,061)	(17,043)	(25,926)	(30,396)
Net earnings	28,793	25,972	61,459	53,617
Less: Net earnings attributable to noncontrolling interests	(191)	(194)	(386)	(356)
Net earnings attributable to Kirby	$ 28,602	$ 25,778	$ 61,073	$ 53,261
Net earnings per share attributable to Kirby common stockholders:
Basic (in dollars per share)	$ 0.48	$ 0.48	$ 1.02	$ 0.99
Diluted (in dollars per share)	$ 0.48	$ 0.48	$ 1.02	$ 0.99
Marine Transportation [Member]
Revenues:
Total revenues	$ 378,163	$ 331,265	$ 718,566	$ 674,917
Distribution and Services [Member]
Revenues:
Total revenues	$ 424,508	$ 142,063	$ 825,793	$ 290,116