Employee Benefit Plans (Tables)

12 Months Ended

Dec. 31, 2015

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

Summary of Company's Stock Option and Restricted Stock Unit Activity

ded December 31, 2015 (in thousands, except per share amounts):

			Stock Options Outstanding				Restricted Stock Units Outstanding
	Shares Available for Grant		Number of Shares		Weighted Average Exercise Price		Number of Units		Weighted Average Grant Date Fair Value
Balance at December 31, 2014	7,480		7,255		$	6.65	2,241		$	6.40
Authorized	350		—		—		—		—
Granted	(4,471	)	1,378		7.29		2,062		7.05
Options exercised	—		(750	)	5.31		—		—
Shares released	—		—		—		(1,721	)	6.47
Forfeited or canceled	2,791		(2,209	)	7.73		(400	)	6.79
Balance at December 31, 2015	6,150		5,674		$	6.56	2,182		$	6.99

The following table summarizes information about stock options outstanding as of December 31, 2015 (in thousands, except per s

Summary of Stock Options Outstanding

are amounts and term):

	Number of Shares	Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (Years)	Aggregate Intrinsic Value
Vested and expected to vest	5,463	$	6.55	3.4	$	236
Exercisable	3,708	6.42		2.4	236

The intrinsic value of options vested and expected to vest and exercisable as of December 31, 2015 is calculated based on the

Summary of Restricted Stock Units Outstanding

pt term):

	Number of Shares Underlying Restricted Stock Units	Weighted Average Remaining Vesting Period (Years)	Aggregate Fair Value
Vested and expected to vest	1,909	0.7	$	8,035

The fair value of restricted stock units vested and expected to vest as of December 31, 2015 is calculated based on the fair v

Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block]

The following table summarizes stock-based compensation expense for all plans (in thousands):

	Year ended December 31,
	2015		2014		2013
Employee stock-based compensation in:
Cost of revenue	$	1,862	$	2,359	$	2,411
Research and development expense	4,435		4,844		4,431
Selling, general and administrative expense	9,285		10,084		9,160
Total stock-based compensation in operating expense	13,720		14,928		13,591
Total employee stock-based compensation recognized in loss from continuing operations	$	15,582	$	17,287	$	16,002

Valuation Assumptions for Stock Options

At the date of grant, the Company estimated the fair value of each stock option grant and purchase right granted under the ESPP using the following weighted average assumptions:

	Employee Stock Options						ESPP
	2015		2014		2013		2015		2014		2013
Expected term (in years)	4.65		4.70		4.70		0.50		0.50		0.50
Volatility	38	%	40	%	50	%	34	%	32	%	31	%
Risk-free interest rate	1.5	%	1.7	%	0.9	%	0.3	%	0.1	%	0.2	%
Dividend yield	0.0	%	0.0	%	0.0	%	0.0	%	0.0	%	0.0	%