Stock Plans (Tables)

12 Months Ended

Dec. 31, 2015

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Stock Options Activity

The following table summarizes total aggregate stock option activity for the year ended December 31, 2015 (in thousands, except for per share data):

	Number of Shares		Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (in years)	Aggregate Intrinsic Value
Balance at December 31, 2014	672		$	12.00
Granted	322		6.72
Exercised	(19	)	6.80
Cancelled	(44	)	11.70
Balance at December 31, 2015	931		$	10.19	3.85	$	196
Vested or expected to vest at December 31, 2015	886		$	10.38	3.57	$	162
Exercisable at December 31, 2015	638		$	11.81	1.34	$	16

Stock Options, Valuation Assumptions

The fair value of the stock options granted during the years ended December 31, 2015 and 2013 was estimated using the Black-Scholes valuation model using the following assumptions:

	Years Ended December 31,
	2015		2013
Expected dividends	—	%	—	%
Expected volatility range	60% to 61%		58% to 69%
Expected volatility weighted average	60	%	63	%
Risk-free interest rate	1.6	%	1.1% to 2.1%
Expected life/term weighted average (in years)	4.9		2.9

Nonvested Restricted Stock Units Activity

The following table summarizes RSU activity for the year ended December 31, 2015 (in thousands, except for per share data):

	Shares		Weighted Average Grant Date Fair Value
Nonvested at December 31, 2014	224		$	10.02
Granted	829		7.02
Vested	(80	)	10.02
Forfeited	(88	)	8.57
Nonvested at December 31, 2015	885		$	7.36

Employee Stock Purchase Plan, Valuation Assumptions

The share price used for the model is a 15% discount on the stock price on the last trading day before the offering period; the number of shares to be purchased is based on employee contributions. The fair value of ESPP awards was calculated using the following weighted-average assumptions:

	Years Ended December 31,
	2015			2014			2013
Expected dividends	—		%	—		%	—		%
Stock price on valuation date	5.97			8.47			7.77
Expected volatility	57		%	77		%	46		%
Risk-free interest rate	0.29		%	0.08		%	0.07		%
Expected life (in years)	0.5			0.4			0.3
Fair value per share	$	1.86		$	4.56		$	2.45

Stock-based Compensation Expense Allocation

Compensation cost for stock options, restricted stock, restricted stock units and the ESPP is as follows (in thousands):

	Years Ended December 31,
	2015		2014		2013
Stock options	$	232	$	52	$	827
Restricted stock	1,974		2,536		2,491
Restricted stock units	1,462		867		592
ESPP	278		512		70
Total stock-based compensation expense	$	3,946	$	3,967	$	3,980

Stock-based compensation cost included in cost of revenue; selling, general and administrative expense; and research and development expense is as follows (in thousands):

	Years Ended December 31,
	2015		2014		2013
Cost of revenue	$	644	$	740	$	1,079
Selling, general and administrative	2,502		2,362		2,140
Research and development	800		865		761
Total stock-based compensation expense	$	3,946	$	3,967	$	3,980

Schedule of Stock Plan Shares Reserved for Future Issuance

The following table summarizes the reservation of shares under the Company's stock-based compensation plans as of December 31, 2015:

2013 Omnibus Equity Incentive Plan	2,200,800
2004 Employee Stock Purchase Plan	307,126
Total	2,507,926

Restricted Stock Awards

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Nonvested Restricted Stock Shares Activity

The following table summarizes RSA activity for the year ended December 31, 2015 (in thousands, except for per share data):

	Shares		Weighted Average Grant Date Fair Value
Nonvested at December 31, 2014	528		$	13.77
Vested	(180	)	15.58
Forfeited	(103	)	10.37
Nonvested at December 31, 2015	245		$	13.87

Restricted Stock Units

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Employee Stock Purchase Plan, Valuation Assumptions

Since the vesting of the market-condition RSUs is dependent on stock price performance, the fair values of these awards were estimated using a Monte-Carlo valuation model with the following weighted-average assumptions:

	Year ended December 31, 2014
Market price at grant per share	$	15.03
Expected dividends	—
Expected volatility	65		%
Risk-free interest rate	0.86		%

Stock-based Compensation Expense Allocation

The following table summarizes the amount of compensation expense recognized for RSUs for the years ended December 31, 2015, 2014 and 2013 (in thousands):

	Years Ended December 31,
	2015			2014		2013
Service-based restricted stock units	$	1,362		$	749	$	592
Performance-based restricted stock units	(28		)	28		—
Market-condition restricted stock units	128			90		—
Total compensation expense recognized for employee restricted stock units	$	1,462		$	867	$	592