Earnings Per Share

12 Months Ended

Dec. 31, 2017

Basic earnings (loss) per share are based on the weighted average number of shares of common stock outstanding. Diluted earnings per share are based upon the weighted average number of shares of common stock outstanding plus all potentially dilutive securities that were assumed to be converted into common shares at the beginning of the period under the treasury stock method. This method requires that the effect of potentially dilutive common stock equivalents be excluded from the calculation of diluted earnings per share for the periods in which net losses are reported because the effect is anti-dilutive.

The following table reconciles the number of common shares used in calculating the basic and diluted net earnings per share:



	December 31,
	2017		2016		2015
Basic average common shares outstanding¹	16,464,286		17,000,599		18,762,451
Incremental shares due to:
Restricted stock units	21,522		21,668		33,128
Performance shares	45,252		76,525		24,717
Stock options	24,866		7,648		—
Diluted average common shares outstanding	16,555,926		17,106,440		18,820,296
Basic net earnings per common share	$	5.91	$	2.91	$	2.98
Diluted net earnings per common share	5.88		2.90		2.97
Anti-dilutive shares excluded from calculation	499,348		220,037		331,168


¹	Basic average common shares outstanding include restricted stock awards that are fully vested, but are deferred for future issuance. See Note 15, "Equity-Based Compensation Plans" for further discussion.