Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Net Income (Loss) Attributable to Parent [Abstract]
Net earnings (loss) attributable to Kirby	$ 122,291	$ (246,954)	$ (272,546)
Undistributed earnings allocated to restricted shares	(33)	0	0
Earnings (loss) available to Kirby common stockholders - basic	122,258	(246,954)	(272,546)
Undistributed earnings allocated to restricted shares	33	0	0
Undistributed earnings reallocated to restricted shares	(33)	0	0
Earnings (loss) available to Kirby common stockholders - diluted	$ 122,258	$ (246,954)	$ (272,546)
Shares outstanding [Abstract]
Weighted average common stock issued and outstanding (in shares)	60,055,000	60,099,000	60,021,000
Weighted average unvested restricted stock (in shares)	(17,000)	(46,000)	(109,000)
Weighted Average Number of Shares Outstanding, Basic (in Shares)	60,038,000	60,053,000	59,912,000
Dilutive effect of stock options and restricted stock units (in shares)	291,000	0	0
Weighted Average Number of Shares Outstanding, Diluted (in Shares)	60,329,000	60,053,000	59,912,000
Net earnings (loss) per share basic attributable to Kirby common stockholders:
Basic (in dollars per share)	$ 2.04	$ (4.11)	$ (4.55)
Net earnings (loss) per share diluted attributable to Kirby common stockholders:
Diluted (in dollars per share)	$ 2.03	$ (4.11)	$ (4.55)
Antidilutive securities excluded from computation of earnings per share (in shares)	400,000	600,000	700,000
RSUs [Member]
Net earnings (loss) per share diluted attributable to Kirby common stockholders:
Antidilutive securities excluded from computation of earnings per share (in shares)	0	7,000	11,000