Stockholders' Equity (Tables)

9 Months Ended

Sep. 30, 2017

Equity [Abstract]

Stock-Based Compensation Expense Related to Grants of Employee and Consultant Stock Options, Restricted Stock and Restricted Stock Units (ZSUs)

We recorded stock-based compensation expense related to grants of employee and consultant stock options, restricted stock, and restricted stock units (“ZSUs”) in our consolidated statements of operations as follows (in thousands):

	Three Months Ended September 30,				Nine Months Ended September 30,
	2017		2016		2017		2016
Cost of revenue	$	435	$	1,049	$	1,425	$	2,825
Research and development		10,097		18,662		32,293		63,078
Sales and marketing		1,891		1,541		5,429		5,738
General and administrative		3,166		3,223		10,199		9,341
Total stock-based compensation expense	$	15,589	$	24,475	$	49,346	$	80,982

Schedule of Share Based Compensation Stock Option Activity

The following table shows stock option activity for the nine months ended September 30, 2017 (in thousands, except weighted-average exercise price and weighted-average contractual term):

	Outstanding Options
				Weighted-		Aggregate		Weighted-
				Average		Intrinsic Value of		Average
				Exercise		Stock Options		Contractual Term
	Stock Options			Price		Outstanding		(in years)
Balance as of December 31, 2016		36,858		$	2.08	$	26,411		6.81
Granted		848			3.62
Forfeited and cancelled		(3,014	)		3.60
Exercised		(2,166	)		1.29
Balance as of September 30, 2017		32,526		$	2.03	$	57,771		6.44

Schedule of Share Based Compensation Restricted Stock Units Award Activity

The following table shows a summary of ZSU activity for the nine months ended September 30, 2017 (in thousands, except weighted-average grant date fair value):

	Outstanding ZSUs
				Weighted-
				Average Grant Date		Aggregate
				Fair Value		Intrinsic Value of
	Shares			(per share)		Unvested ZSUs
Unvested as of December 31, 2016		59,452		$	2.66	$	152,792
Granted		16,262			3.36
Vested		(15,941	)		2.84
Forfeited and cancelled		(13,862	)		2.63
Unvested as of September 30, 2017		45,911		$	2.86	$	173,544

Schedule of Accumulated Other Comprehensive Income Loss

The following table shows a summary of changes in accumulated other comprehensive income (loss) by component for the nine months ended September 30, 2017 (in thousands):

	Foreign Currency Translation			Unrealized Gains (Losses) on Available-for-Sale Securities			Total
Balance as of December 31, 2016	$	(128,671	)	$	(23	)	$	(128,694	)
Other comprehensive income (loss) before    reclassifications		37,479			(8	)		37,471
Less: Amounts reclassified from accumulated other    comprehensive income (loss)		—			—			—
Net current-period other comprehensive income (loss)		37,479			(8	)		37,471
Balance as of September 30, 2017	$	(91,192	)	$	(31	)	$	(91,223	)