Earnings Per Share

12 Months Ended

Dec. 31, 2020

Earnings Per Share [Abstract]

Earnings Per Share

(10) Earnings Per Share

The following table presents the components of basic and diluted earnings per share (in thousands, except per share amounts):

	Year Ended December 31,
	2020			2019			2018
Net earnings (loss) attributable to Kirby	$	(272,546	)	$	142,347		$	78,452
Undistributed earnings allocated to restricted shares		—			(369	)		(324	)
Income (loss) available to Kirby common stockholders — basic		(272,546	)		141,978			78,128
Undistributed earnings allocated to restricted shares		—			369			324
Undistributed earnings reallocated to restricted shares		—			(369	)		(323	)
Income (loss) available to Kirby common stockholders — diluted	$	(272,546	)	$	141,978		$	78,129
Shares outstanding:
Weighted average common stock issued and outstanding		60,021			59,905			59,804
Weighted average unvested restricted stock		(109	)		(155	)		(247	)
Weighted average common stock outstanding — basic		59,912			59,750			59,557
Dilutive effect of stock options and restricted stock units		—			159			132
Weighted average common stock outstanding — diluted		59,912			59,909			59,689
Net earnings (loss) per share attributable to Kirby common stockholders:
Basic	$	(4.55	)	$	2.38		$	1.31
Diluted	$	(4.55	)	$	2.37		$	1.31

Certain outstanding options to purchase approximately 681,000, 187,000, and 384,000 shares of common stock were excluded in the computation of diluted earnings per share as of December 31, 2020, 2019, and 2018, respectively, as such stock options would have been antidilutive.  Certain outstanding RSUs to convert to 11,000 shares of common stock were also excluded in the computation of diluted earnings per share as of December 31, 2020, as such RSUs would have been antidilutive.  No RSUs were antidilutive at December 31, 2019.