Stockholders' Equity (Tables)

6 Months Ended

Jun. 30, 2018

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

Stock option activity under the equity incentive plans was as follows (in thousands, except per share amounts):



	Stock Options Outstanding
	Number of Shares Subject to Stock Options		Weighted– Average Exercise Price		Aggregate Intrinsic Value ⁽¹⁾
Balance—December 31, 2017	21,386		$	3.01
Granted	—		—
Exercised	(1,768	)	2.55
Forfeited or canceled	(561	)	7.02
Balance—June 30, 2018	19,057		2.93		$	58,535

Stock options vested and expected to vest—June 30, 2018	19,057		2.93		58,535
Stock options exercisable—June 30, 2018	16,654		2.61		55,317

⁽¹⁾ The aggregate intrinsic values of stock options outstanding, exercisable, vested and expected to vest as of June 30, 2018 were calculated as the difference between the exercise price of the stock options and the fair value of the Class A common stock of $6.53 as of June 30, 2018.

Schedule of restricted stock unit activity

RSU activity under the equity incentive plans was as follows (in thousands, except per share amounts):



	RSUs Outstanding		Weighted- Average Grant Date Fair Value
Unvested balance—December 31, 2017	19,188		$	9.13
Granted	12,557		5.02
Vested	(4,810	)	8.80
Forfeited or canceled	(3,135	)	8.24
Unvested balance—June 30, 2018	23,800		$	7.15

Schedule of stock-based compensation expense

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



	Three Months Ended				Six Months Ended
	June 30, 2018		July 1, 2017		June 30, 2018		July 1, 2017
Cost of revenue	$	2,032	$	1,492	$	3,130	$	1,510
Research and development	15,090		12,648		29,761		27,333
Sales and marketing	3,911		3,987		7,358		7,622
General and administrative	4,824		3,839		9,249		7,994
Total stock-based compensation expense	$	25,857	$	21,966	$	49,498	$	44,459