Stockholders' Equity (Tables)

6 Months Ended

Jun. 30, 2020

Share-based Payment Arrangement [Abstract]

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

he fair value of each option grant is estimated on the date of grant, adjusted for estimated forfeitures, using the Black-Scholes option-pricing model with the following weighted average assumptions:

	Three Months Ended June 30,		Six Months Ended June 30,
	2020	2019	2020	2019
Dividend yield	0.0%	0.0%	0.0%	0.0%
Risk-free interest rate	0.31%-0.32%	1.88% - 2.36%	0.31%-0.66%	1.88% - 2.57%
Expected life (in years)	5	5	5	5
Historical volatility	51.91%-51.94%	43.42% - 43.69%	46.5%-51.94%	43.42% - 43.85%

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, 2019	5,799		$	16.57	6.79	119,064
Granted	619
Exercised	(603	)
Cancelled or expired	(405	)
Balance outstanding at June 30, 2020	5,410		$	18.01	6.58	$	126,716
Options vested and expected to vest	1,603		$	21.17	8.35	$	32,477
Options exercisable at June 30, 2020	2,978		$	13.98	4.95	$	81,744

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, 2019	3,049		$	24.73	$	112,848
Awarded	2,294
Vested	(1,503	)
Forfeited	(490	)
Non-vested and outstanding at June 30, 2020	3,350		$	24.89	$	138,789
Expected to vest	2,048		$	24.16	$	84,850