Stockholders' Equity (Tables)

9 Months Ended

Sep. 30, 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	1,150		5.63
Exercised	(6,634	)	1.15
Forfeited or canceled	(6,775	)	9.59
Balance—September 30, 2017	22,195		2.99		$	93,199

Stock options exercisable—September 30, 2017	16,455		2.42		77,220
Stock options vested and expected to vest—September 30, 2017	22,084		2.99		92,872

⁽¹⁾ The aggregate intrinsic values of stock options outstanding, exercisable, vested and expected to vest as of September 30, 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 $6.96 as of September 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	14,499		6.55
Vested	(4,673	)	12.81
Forfeited or canceled	(3,909	)	12.94
Unvested balance—September 30, 2017	17,495		10.27

Schedule of stock-based compensation expense

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



	Three Months Ended				Nine Months Ended
	September 30, 2017		October 1, 2016		September 30, 2017		October 1, 2016

Cost of revenue	$	1,379	$	1,014	$	2,889	$	3,407
Research and development	12,947		12,314		40,280		34,432
Sales and marketing	3,679		3,030		11,301		8,492
General and administrative	4,792		3,647		12,786		11,844
Total stock-based compensation expense	$	22,797	$	20,005	$	67,256	$	58,175