Stockholders' Equity (Tables)

3 Months Ended

Mar. 31, 2019

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Weighted Average Assumptions of Fair Value Options Using Black-Scholes Option-Pricing Model

The fair value of each option grant is estimated on the date of grant using the Black-Scholes option-pricing model with the following weighted average assumptions:

	Three Months Ended
	March 31,
	2019	2018
Dividend yield	0.0%	0.0%
Risk-free interest rate	2.49% - 2.57%	2.5% - 2.7%
Expected life (in years)	5	5
Historical volatility	43.62% - 43.85%	47.9% - 48.2%

Summary of Stock Option Activity and Weighted Average Exercise Prices

A summary of the Company’s stock option activity and weighted average exercise prices follows:

	Stock Option Activity				Weighted Average Remaining Contractual Term (in years)	Aggregate Intrinsic Value (in thousands)
	Options (in thousands)		Weighted Average Exercise Price
Balance outstanding at December 31, 2018	6,266		$	12.13
Granted	241		23.75
Exercised	(626	)	10.36
Cancelled or expired	(124	)	11.96
Balance outstanding at March31, 2019	5,757		$	12.81	6.73	$	93,297
Options vested and expected to vest	5,157		$	12.50	6.48	$	85,169
Options exercisable at March 31, 2019	3,093		$	11.38	4.97	$	54,556

Schedule of Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range

The following table summarizes information about outstanding and vested stock options as of March 31, 2019:

	Options Outstanding				Options Exercisable
Range of Exercise Prices	Number of Shares Outstanding (in thousands)	Weighted-Average Remaining Contractual Life (Years)	Weighted-Average Exercise Price		Number of Shares (in thousands)	Weighted-Average Exercise Price
$3.35 - $7.60	903	6.47	$	7.30	475	$	7.15
$7.95 - $10.01	655	6.35	9.33		535	9.35
$10.05 - $10.60	664	5.72	10.26		658	10.26
$11.33 - $12.32	360	7.06	11.81		176	11.77
$12.45 - $12.45	855	2.85	12.45		158	12.45
$12.46 - $13.59	643	9.38	13.30		643	13.30
$14.30 - $16.05	580	3.76	14.84		149	15.08
$16.35 - $21.05	621	8.72	17.76		299	17.46
$21.10 - $25.36	360	6.92	22.67		—	—
$25.95 - $25.95	116	9.82	25.95		—	—
	5,757	6.91	$	12.81	3,093	$	11.38

Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity

A summary of the Company’s restricted stock units (“RSUs”) activity and weighted average exercise prices follows:

	Restricted Stock Unit Activity
	Number of Shares (in thousands)		Weighted Average Grant Date Fair Value (Per Share)		Aggregate Fair Value (in thousands)
Balance outstanding at December 31, 2018	2,690		$	15.81	$	—
Awarded	386		25.07		—
Released	(415	)	12.18		—
Forfeited	(87	)	15.87		—
Non-vested and outstanding at March 31 2019	2,574		$	17.61	$	74,719
Expected to vest	1,816		$	16.80	$	52,686