Stock-based Compensation (Tables)

9 Months Ended

Sep. 30, 2013

Stock-based Compensation Expense

The stock-based compensation expense related to all of our stock-based awards and employee stock purchases for the three and nine months ended September 30, 2013 and 2012 is as follows (in thousands):

	Three Months Ended September 30,				Nine Months Ended September 30,
	2013		2012		2013		2012
Cost of net revenues	$	664	$	445	$	1,881	$	1,365
Sales and marketing	2,215		1,448		5,238		4,066
General and administrative	3,687		2,657		11,170		7,579
Research and development	1,024		812		2,976		2,494
Total stock-based compensation expense	$	7,590	$	5,362	$	21,265	$	15,504

Stock Option Activity

Activity for the nine month period ended September 30, 2013 under the stock option plans is set forth below (in thousands, except years and per share amounts):

	Stock Options Number of Shares Underlying Stock Options		Weighted Average Exercise Price per Share		Weighted Average Remaining Contractual Term	Aggregate Intrinsic Value
					(in years )
Outstanding as of December 31, 2012	3,276
Granted	—
Exercised	(1,430	)
Cancelled or expired	(79	)
Outstanding as of September 30, 2013	1,767		$	15.53	3.77	$	57,550
Vested and expected to vest at September 30, 2013	1,760		$	15.51	3.77	$	57,368
Exercisable at September 30, 2013	1,561		$	15.02	3.74	$	51,635

^[1]

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

The fair value of the option component of the 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,
	2013			2012			2013			2012
Employee Stock Purchase Plan:
Expected term (in years)	1.2			1.2			1.2			1.2
Expected volatility	37.3		%	48.0		%	44.9		%	49.7		%
Risk-free interest rate	0.2		%	0.2		%	0.2		%	0.2		%
Expected dividends	—			—			—			—
Weighted average fair value at grant date	$	13.84		$	11.99		$	11.70		$	11.10

Restricted Stock Units (RSUs)

Summary Of Nonvested Shares

A summary of the RSU activity for the nine months ended September 30, 2013 is as follows (in thousands, except years):

	Number of Shares Underlying RSU		Weighted Remaining Vesting Period	Aggregate Intrinsic Value
			(in years)
Nonvested as of December 31, 2012	1,500
Granted	1,130
Vested and released	(529	)
Forfeited	(98	)
Nonvested as of September 30, 2013	2,003		1.59	$	96,335

Market Performance Based Restricted Stock Units

Summary Of Nonvested Shares

The following table summarizes the MSU activity for the nine months ended September 30, 2013 (in thousands, except years):

	Number of Shares Underlying MSU		Weighted Average Remaining Vesting Period	Aggregate Intrinsic Value
			(in years )
Nonvested as of December 31, 2012	266
Granted	225
Vested and released	(96	)
Forfeited	(43	)
Nonvested as of September 30, 2013	352		1.83	$	16,950

[1] There were no stock options granted during the three and nine months ended September 30, 2013 and 2012.