EARNINGS PER SHARE

Basic earnings per share is computed by dividing the net income (loss) from continuing operations attributable to common stockholders by the weighted average number of common shares outstanding during the period. Diluted earnings per share is calculated based on the combined weighted average number of common shares and potentially dilutive shares, which include the assumed exercise of employee stock options, including market-based performance stock options based on the expected achievement of performance targets, unvested restricted stock awards, unvested restricted stock units and unvested performance stock units, including market-based performance units based on the expected achievement of performance targets. In computing diluted earnings per share, we utilize the treasury stock method.

A summary of the numerator and denominators used in the computation of earnings per share follows:



	Three Months Ended September 30,						Nine Months Ended September 30,
	2017			2016			2017			2016
Numerator:
Net income (loss) attributable to common stockholders	$	12,080		$	7,537		$	(41,820	)	$	5,125
Denominators:
Number of shares outstanding, end of period:
Class A common stock	41,055			40,500			41,055			40,500
Class B common stock	988			988			988			988
Unvested restricted stock	(82		)	(109		)	(82		)	(109		)
Effect of weighted average shares outstanding	(10		)	(2		)	(178		)	(210		)
Basic weighted average common shares outstanding	41,951			41,377			41,783			41,169
Impact of potentially dilutive securities:
Dilutive effect of stock options and other stock awards	1,344			910			—			727
Diluted weighted average common shares outstanding	43,295			42,287			41,783			41,896
Anti-dilutive potentially issuable shares	—			322			2,560			322