v3.25.2
Earnings Per Share (Details) - USD ($)
$ / shares in Units, $ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Jun. 30, 2025
Jun. 30, 2024
Net Income (Loss) Attributable to Parent [Abstract]        
Net earnings attributable to Kirby $ 94,277 $ 83,854 $ 170,263 $ 153,922
Undistributed earnings allocated to restricted shares (17) (13) (15) (13)
Earnings available to Kirby common stockholders - basic 94,260 83,841 170,248 153,909
Undistributed earnings allocated to restricted shares 17 13 15 13
Undistributed earnings reallocated to restricted shares (17) (13) (15) (13)
Earnings available to Kirby common stockholders - diluted $ 94,260 $ 83,841 $ 170,248 $ 153,909
Shares outstanding [Abstract]        
Weighted average common stock issued and outstanding (in shares) 56,115,000 58,190,000 56,525,000 58,329,000
Weighted average unvested restricted stock (in shares) (10,000) (9,000) (5,000) (5,000)
Weighted average common stock outstanding - basic (in shares) 56,105,000 58,181,000 56,520,000 58,324,000
Dilutive effect of stock options and restricted stock units (in shares) 332,000 411,000 349,000 379,000
Weighted average common stock outstanding - diluted 56,437,000 58,592,000 56,869,000 58,703,000
Net earnings per share basic attributable to Kirby common stockholders:        
Basic $ 1.68 $ 1.44 $ 3.01 $ 2.64
Net earnings per share diluted attributable to Kirby common stockholders:        
Diluted $ 1.67 $ 1.43 $ 2.99 $ 2.62
Stock Options [Member]        
Net earnings per share diluted attributable to Kirby common stockholders:        
Antidilutive securities excluded from computation of earnings per share (in shares)     0 0
RSUs [Member]        
Net earnings per share diluted attributable to Kirby common stockholders:        
Antidilutive securities excluded from computation of earnings per share (in shares)     0 0