Stockholders' Equity and Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2017

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Nonvested Restricted Stock Unit Awards

The following table summarizes restricted stock awards activity for the six months ended June 30, 2017:

	Time-Based					Market-Based
	Restricted Stock Awards					Restricted Stock Awards
	Shares			Weighted Average Grant Date Fair Value		Shares			Weighted Average Grant Date Fair Value
Unvested shares of restricted stock   outstanding at December 31, 2016		1,429,514		$	18.38		738,425		$	28.68
Granted		309,526		$	60.00		314,021		$	48.62
Vested		(590,029	)	$	5.29		(477,325	)	$	27.93
Forfeited		(51,111	)	$	36.24		(16,166	)	$	33.47
Unvested shares of restricted stock   outstanding at June 30, 2017		1,097,900		$	36.32		558,955		$	40.39