Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2017

Stock-Based Compensation

Summary of stock options outstanding, vested and exercisable

				Weighted
		Weighted		average
		average		remaining	Aggregate
	Outstanding	exercise price		contractual life	Intrinsic Value
	Options	per share		(Years)	(in thousands)
Outstanding at December 31, 2016	5,997,372	$	10.18	7.30	$	145,270
Granted	534,262		34.39			—
Forfeited	(35,008)		12.58			—
Exercised	(1,096,999)		6.86			—
Expired	(2,893)		13.79			—
Outstanding at March 31, 2017	5,396,734	$	13.23	7.56	$	153,263
Vested, exercisable, expected to vest
at March 31, 2017	5,396,734	$	13.23	7.56	$	153,263
Exercisable at March 31, 2017	3,188,518	$	9.95	6.99	$	101,004

Summary of restricted stock units activity

		Weighted
		average
		grant date fair value
	Number of Awards	per share
Outstanding at December 31, 2016	67,295	$	25.88
Granted	235,412		34.39
Forfeited	(3,875)		24.70
Vested and converted to shares, net of units withheld for taxes	(131)		19.00
Units withheld for taxes	(77)		19.00
Outstanding at March 31, 2017	298,624	$	32.59
Expected to vest at March 31, 2017	298,624	$	32.59

Schedule of weighted average assumptions to estimate the fair value of stock options granted

	Three Months Ended March 31,
		2017
Expected term (years)			6.25
Expected volatility			40.00	%
Expected dividend yield			0.00	%
Weighted average risk-free interest rate			1.93	%
Weighted average grant date fair value		$	14.45