Stockholders' Equity (Tables)

9 Months Ended

Sep. 30, 2019

Stockholders' Equity Note [Abstract]

Stock-based Compensation Expense

The stock-based compensation related to all of our stock-based awards and employee stock purchases for the three and nine months ended September 30, 2019 and 2018 is as follows (in thousands): 

	Three Months Ended September 30,				Nine Months Ended September 30,
	2019		2018		2019		2018
Cost of net revenues	$	1,354	$	966	$	3,744	$	2,747
Selling, general and administrative	19,394		15,403		54,321		41,197
Research and development	3,428		2,829		9,622		7,974
Total stock-based compensation	$	24,176	$	19,198	$	67,687	$	51,918

Summary Of Restricted Stock Units

A summary for the nine months ended September 30, 2019 is as follows:

 

	Number of Shares Underlying RSUs (in thousands)		Weighted Average Grant Date Fair Value		Weighted  Average Remaining Contractual Term (in years)	Aggregate Intrinsic  Value (in thousands)
Nonvested as of December 31, 2018	931		$	129.39
Granted	276		256.33
Vested and released	(422	)	103.01
Forfeited	(61	)	181.57
Nonvested as of September 30, 2019	724		$	188.86	1.3	$	131,021

Summary Of Market-performance Based Restricted Stock Units

A summary for the nine months ended September 30, 2019 is as follows: 

	Number of Shares Underlying MSUs (in thousands)		Weighted Average Grant Date Fair Value		Weighted Average Remaining Contractual Term (in years)	Aggregate Intrinsic  Value (in thousands)
Nonvested as of December 31, 2018	324		$	215.07
Granted	138		240.73
Vested and released	(191	)	77.17
Forfeited	(12	)	258.72
Nonvested as of September 30, 2019	259		$	326.15	1.4	$	46,776

Schedule of Share-based Payment Award, Employee Stock Purchase Plan, Valuation Assumptions

The fair value of the option component of the 2010 Purchase Plan shares was estimated at the grant date using the Black-Scholes option pricing model with the following weighted average assumptions:

	Three Months Ended September 30,						Nine Months Ended September 30,
	2019			2018			2019			2018
Expected term (in years)	1.5			1.2			1.4			1.3
Expected volatility	52.0		%	35.7		%	50.1		%	35.2		%
Risk-free interest rate	1.8		%	2.5		%	2.2		%	2.2		%
Expected dividends	—			—			—			—
Weighted average fair value at grant date	$	80.42		$	109.58		$	86.02		$	94.71