STOCK-BASED COMPENSATION (Tables)

6 Months Ended

Jun. 30, 2015

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

Summary of Stock Option Activity

The following is a summary of stock option activity for the six months ended June 30, 2015 (in thousands, except per share data):

	Number of Shares Outstanding		Weighted- Average Exercise Price per Share
Outstanding at December 31, 2014	8,632		$	4.75
Granted	737		11.22
Exercised	(288	)	4.34
Canceled	(194	)	10.19
Outstanding at June 30, 2015	8,887		5.18

Summary of Restricted Stock Unit Activity

The following is a summary of restricted stock unit activity for the six months ended June 30, 2015 (in thousands, except per share data):

	RSUs		Weighted Average Fair Value per Share at Grant Date
Outstanding at December 31, 2014	1,345		$	8.25
Granted	613		12.25
Vested	(212	)	7.79
Canceled	(43	)	13.13
Outstanding at June 30, 2015	1,703		9.62

Summary of the Components of Total Stock-Based Compensation Expense

The following table summarizes the components of total stock-based compensation expense included in the condensed consolidated statements of operations for the periods presented (in thousands):

	Three Months Ended June 30,				Six Months Ended June 30,
	2015		2014		2015		2014
Cost of revenues	$	318	$	194	$	582	$	343
Research and development	1,158		778		2,238		1,391
Sales and marketing	942		649		1,707		1,181
General and administrative	889		873		1,769		1,592
Total	$	3,307	$	2,494	$	6,296	$	4,507

Summary of Stock-Based Compensation Associated with Each Type of Award

The following table summarizes stock-based compensation associated with stock options, restricted stock units, and employee stock purchase plan shares for the periods presented (in thousands):

	Three Months Ended June 30,				Six Months Ended June 30,
	2015		2014		2015		2014
Stock options and restricted stock units	$	2,874	$	2,309	$	5,400	$	4,148
Employee stock purchase plan	433		185		896		359
Total	$	3,307	$	2,494	$	6,296	$	4,507

Summary of the Weighted-Average Grant Date Fair Value of Options Granted

The following table presents the weighted-average grant date fair value of options granted for the periods presented and the assumptions used to estimate those values using a Black-Scholes option pricing model:

	Three Months Ended June 30,						Six Months Ended June 30,
	2015			2014			2015			2014
Weighted average grant date fair value	$	6.90		$	4.24		$	6.38		$	4.13
Expected term (in years)	4.4			4.3			4.5			4.4
Expected volatility	72.7		%	69.5		%	72.0		%	66.4		%
Annual risk-free rate of return	1.3		%	1.4		%	1.3		%	1.4		%
Dividend yield	0.0		%	0.0		%	0.0		%	0.0		%