Employee Benefit Plans and Stock-based Compensation (Tables)

3 Months Ended

Mar. 31, 2017

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

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

			Stock Options Outstanding				RSUs 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, 2016	3,912		5,019		$	6.01	3,864		$	4.26
Authorized	—		—		—		—		—
Granted	(3,181	)	30		5.10		2,100		5.49
Options exercised	—		(81	)	3.00		—		—
Shares released	—		—		—		(1,672	)	3.93
Forfeited	748		(287	)	6.41		(308	)	4.24
Balance at March 31, 2017	1,479		4,681		$	6.04	3,984		$	5.05

Summary of Stock Options Outstanding

The following table summarizes information about stock options outstanding as of March 31, 2017 (in thousands, except per share amounts and terms):

	Number of Shares	Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (Years)	Aggregate Intrinsic Value
Vested and expected to vest	4,681	$	6.04	3.9	$	3,200
Exercisable	3,350	6.38		3.2	1,446

Summary of Restricted Stock Units Outstanding

The following table summarizes information about RSUs and PRSUs outstanding as of March 31, 2017 (in thousands, except term):

	Number of Shares Underlying Restricted Stock Units	Weighted Average Remaining Vesting Period (Years)	Aggregate Fair Value
Vested and expected to vest	3,573	1.1	$	21,260

Schedule of Defined Benefit Plans Obligations

The table below shows the components of net periodic benefit costs (in thousands):

	Three months ended
	March 31, 2017		April 1, 2016
Service cost	$	55	$	23
Interest cost	16		10
Recognized net actuarial loss	1		—
Net periodic benefit cost included in operating loss	$	72	$	33

Summary of Stock-Based Compensation Expense

Stock-based Compensation

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

	Three months ended
	March 31, 2017		April 1, 2016
Stock-based compensation in:
Cost of revenue	$	445	$	227
Research and development expense	977		969
Selling, general and administrative expense	1,829		1,898
Total stock-based compensation in operating expense	2,806		2,867
Total stock-based compensation	$	3,251	$	3,094

Valuation Assumptions for Stock Options

	Employee Stock Options
	Three months ended
	March 31, 2017		April 1, 2016
Expected term (years)	4.30		4.30
Volatility	42	%	36	%
Risk-free interest rate	1.8	%	1.4	%
Expected dividends	0.0	%	0.0	%

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

	ESPP Purchase Period Ending
	July 3, 2017		June 30, 2016
Expected term (years)	0.50		0.5
Volatility	63	%	52	%
Risk-free interest rate	0.8	%	0.5	%
Expected dividends	0.0	%	0.0	%
Estimated weighted average fair value per share at purchase date	$1.71		$1.17