Quarterly Results (Schedule Of Quarterly Results) (Unaudited) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Quarterly Results (Unaudited) [Abstract]
Revenues	$ 568,397	$ 551,105	$ 563,908	$ 558,785	$ 512,551	$ 521,324	$ 511,848	$ 566,935	$ 2,242,195	$ 2,112,658	$ 1,850,417
Costs and expenses	459,813	432,991	455,193	458,904	413,098	428,647	428,219	477,847	1,806,013	1,747,825	1,538,074
Gain (loss) on disposition of assets	160	223	537	(32)	(15)	(40)	69	(28)	(888)	14	40
Operating income	108,744	118,337	109,252	99,849	99,438	92,637	83,698	89,060	436,182	364,833	312,343
Other income (expense)	132	60	101	75	(45)	(56)	30	149	20	(198)	(41)
Interest expense	(5,971)	(6,694)	(7,219)	(7,988)	(6,588)	(6,056)	(5,901)	(5,840)	(27,872)	(24,385)	(17,902)
Earnings before taxes on income	102,905	111,703	102,134	91,936	92,805	86,525	77,827	83,369	408,678	340,526	294,747
Provision for taxes on income	(37,646)	(42,007)	(38,342)	(34,384)	(34,231)	(32,794)	(29,392)	(31,490)	(152,379)	(127,907)	(109,255)
Net earnings	65,259	69,696	63,792	57,552	58,574	53,731	48,435	51,879	256,299	212,619	185,492
Less: Net earnings attributable to noncontrolling interests	(992)	(573)	(699)	(974)	(686)	(676)	(884)	(935)	(3,238)	(3,181)	(2,466)
Net earnings attributable to Kirby	$ 64,267	$ 69,123	$ 63,093	$ 56,578	$ 57,888	$ 53,055	$ 47,551	$ 50,944	$ 253,061	$ 209,438	$ 183,026
Net earnings per share attributable to Kirby common stockholders [Abstract]
Basic (in dollars per share)	$ 1.13	$ 1.22	$ 1.11	$ 1.00	$ 1.03	$ 0.95	$ 0.85	$ 0.91	$ 4.46	$ 3.75	$ 3.35
Diluted (in dollars per share)	$ 1.13	$ 1.21	$ 1.11	$ 1.00	$ 1.03	$ 0.95	$ 0.85	$ 0.91	$ 4.44	$ 3.73	$ 3.33