CONSOLIDATED STATEMENTS OF EARNINGS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues:
Total revenues	$ 2,171,408	$ 2,838,399	$ 2,970,697
Costs and expenses:
Costs of sales and operating expenses	1,510,818	2,030,046	2,160,946
Selling, general and administrative	258,272	277,388	304,397
Taxes, other than on income	42,000	41,933	39,251
Depreciation and amortization	219,921	219,632	224,972
Impairments and other charges	561,274	35,525	85,407
Lease cancellation costs	0	0	2,403
Gain on disposition of assets	(118)	(8,152)	(1,968)
Total costs and expenses	2,592,167	2,596,372	2,815,408
Operating income (loss)	(420,759)	242,027	155,289
Other income	8,147	3,787	5,726
Interest expense	(48,739)	(55,994)	(46,856)
Earnings (loss) before taxes on income	(461,351)	189,820	114,159
(Provision) benefit for taxes on income	189,759	(46,801)	(35,081)
Net earnings (loss)	(271,592)	143,019	79,078
Less: Net earnings attributable to noncontrolling interests	(954)	(672)	(626)
Net earnings (loss) attributable to Kirby	$ (272,546)	$ 142,347	$ 78,452
Net earnings (loss) per share attributable to Kirby common stockholders:
Basic (in dollars per share)	$ (4.55)	$ 2.38	$ 1.31
Diluted (in dollars per share)	$ (4.55)	$ 2.37	$ 1.31
Marine Transportation [Member]
Revenues:
Total revenues	$ 1,404,265	$ 1,587,082	$ 1,483,143
Distribution and Services [Member]
Revenues:
Total revenues	$ 767,143	$ 1,251,317	$ 1,487,554