Stock Plan (Tables)

6 Months Ended

Jul. 01, 2017

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

Stock option activity under the equity incentive plans was as follows:



	Stock Options Outstanding
	Number of Shares Subject to Stock Options		Weighted– Average Exercise Price		Aggregate Intrinsic Value ⁽¹⁾
	(in thousands)				(in thousands)
Balance—December 31, 2016	34,454		$	3.85
Granted	—
Exercised	(3,850	)	$	1.32
Forfeited or canceled	(2,562	)	$	7.26
Balance—July 1, 2017	28,042		$	3.88	$	85,564

Stock options exercisable—July 1, 2017	20,405		$	3.08	$	72,752
Stock options vested and expected to vest—July 1, 2017	27,831		$	3.87	$	85,240

⁽¹⁾ The aggregate intrinsic values of stock options outstanding, exercisable, vested and expected to vest as of July 1, 2017 were calculated as the difference between the exercise price of the stock options and the fair value of the Class A common stock of $5.31 as of June 30, 2017.

Schedule of restricted stock unit activity

RSU activity under the equity incentive plans was as follows:



	RSUs Outstanding		Weighted- Average Grant Date Fair Value
	(in thousands)
Unvested balance—December 31, 2016	11,578		$	16.85
Granted	9,929		5.75
Vested	(2,354	)	15.69
Forfeited or canceled	(2,712	)	13.86
Unvested balance—July 1, 2017	16,441		10.81

Schedule of stock-based compensation expense

Total stock-based compensation expense recognized was as follows (in thousands):



	Three Months Ended				Six Months Ended
	July 1, 2017		July 2, 2016		July 1, 2017		July 2, 2016

Cost of revenue	$	1,492	$	1,084	$	1,510	$	2,393
Research and development	12,648		11,725		27,333		22,118
Sales and marketing	3,987		2,927		7,622		5,462
General and administrative	3,839		4,664		7,994		8,197
Total stock-based compensation expense	$	21,966	$	20,400	$	44,459	$	38,170