Basis for Preparation of the Condensed Financial Statements (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018
Condensed Balance Sheet [Abstract]
Goodwill	$ 576,165		$ 953,826
Total assets	6,009,644		6,079,097
Deferred income taxes	552,990		588,204
Total long-term liabilities	2,487,558		2,193,390
Retained earnings	2,518,698		2,865,939
Total Kirby stockholders' equity	3,022,709		3,368,623
Total equity	3,025,754	$ 3,265,408	3,371,592	$ 3,216,301
Total liabilities and equity	6,009,644		6,079,097
Condensed Statement of Earnings [Abstract]
Impairments and other charges	561,274	0
Total costs and expenses	1,153,622	672,515
Operating income (loss)	(509,696)	72,106
Earnings (Loss loss) before taxes on income	(519,772)	58,337
(Provision) Benefit benefit for taxes on income	172,809	(13,880)
Net earnings (loss)	(346,963)	44,457
Net earnings (loss) attributable to Kirby	$ (347,241)	44,296
Loss per common share - basic and diluted (in dollars per share)	$ (5.80)
Condensed Statement of Comprehensive Income [Abstract]
Net earnings (loss)	$ (346,963)	44,457
Total comprehensive income (loss), net of taxes	(348,155)	44,997
Comprehensive income (loss) attributable to Kirby	(348,433)	44,836
Condensed Statement of Cash Flows [Abstract]
Net earnings (loss)	(346,963)	44,457
Provision (Bbenefit) for deferred income taxes	(35,242)	12,490
Impairments and other charges	561,274	0
Condensed Statement of Stockholders' Equity [Abstract]
Total comprehensive income (loss), net of taxes	(348,155)	44,997
Retained earnings	2,518,698		2,865,939
Total equity	3,025,754	$ 3,265,408	$ 3,371,592	$ 3,216,301
Previously Reported [Member]
Condensed Balance Sheet [Abstract]
Goodwill	704,098
Total assets	6,137,577
Deferred income taxes	582,150
Total long-term liabilities	2,516,718
Retained earnings	2,617,471
Total Kirby stockholders' equity	3,121,482
Total equity	3,124,527
Total liabilities and equity	6,137,577
Condensed Statement of Earnings [Abstract]
Impairments and other charges	433,341
Total costs and expenses	1,025,689
Operating income (loss)	(381,763)
Earnings (Loss loss) before taxes on income	(391,839)
(Provision) Benefit benefit for taxes on income	143,649
Net earnings (loss)	(248,190)
Net earnings (loss) attributable to Kirby	$ (248,468)
Loss per common share - basic and diluted (in dollars per share)	$ (4.15)
Condensed Statement of Comprehensive Income [Abstract]
Net earnings (loss)	$ (248,190)
Total comprehensive income (loss), net of taxes	(249,382)
Comprehensive income (loss) attributable to Kirby	(249,660)
Condensed Statement of Cash Flows [Abstract]
Net earnings (loss)	(248,190)
Provision (Bbenefit) for deferred income taxes	(6,082)
Impairments and other charges	433,341
Condensed Statement of Stockholders' Equity [Abstract]
Total comprehensive income (loss), net of taxes	(249,382)
Retained earnings	2,617,471
Total equity	3,124,527
Adjustment [Member]
Condensed Balance Sheet [Abstract]
Goodwill	(127,933)
Total assets	(127,933)
Deferred income taxes	(29,160)
Total long-term liabilities	(29,160)
Retained earnings	(98,773)
Total Kirby stockholders' equity	(98,773)
Total equity	(98,773)
Total liabilities and equity	(127,933)
Condensed Statement of Earnings [Abstract]
Impairments and other charges	127,933
Total costs and expenses	127,933
Operating income (loss)	(127,933)
Earnings (Loss loss) before taxes on income	(127,933)
(Provision) Benefit benefit for taxes on income	29,160
Net earnings (loss)	(98,773)
Net earnings (loss) attributable to Kirby	$ (98,773)
Loss per common share - basic and diluted (in dollars per share)	$ (1.65)
Condensed Statement of Comprehensive Income [Abstract]
Net earnings (loss)	$ (98,773)
Total comprehensive income (loss), net of taxes	(98,773)
Comprehensive income (loss) attributable to Kirby	(98,773)
Condensed Statement of Cash Flows [Abstract]
Net earnings (loss)	(98,773)
Provision (Bbenefit) for deferred income taxes	(29,160)
Impairments and other charges	127,933
Condensed Statement of Stockholders' Equity [Abstract]
Total comprehensive income (loss), net of taxes	(98,773)
Retained earnings	(98,773)
Total equity	$ (98,773)