Stockholders' Equity (Tables)

6 Months Ended

Jun. 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 June 30,				Six Months Ended June 30,
	2017		2016		2017		2016
Cost of revenue	$	371	$	1,127	$	990	$	1,776
Research and development		10,483		20,213		22,196		44,416
Sales and marketing		1,751		2,206		3,538		4,197
General and administrative		3,627		3,353		7,034		6,118
Total stock-based compensation expense	$	16,232	$	26,899	$	33,758	$	56,507

Schedule of Share Based Compensation Stock Option Activity

The following table shows stock option activity for the six months ended June 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		(2,514	)		3.58
Exercised		(1,633	)		0.91
Balance as of June 30, 2017		33,559		$	2.06	$	54,062		6.67

Schedule of Share Based Compensation Restricted Stock Units Award Activity

The following table shows a summary of ZSU activity for the six months ended June 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		15,177			3.34
Vested		(12,430	)		2.85
Forfeited and cancelled		(10,919	)		2.51
Unvested as of June 30, 2017		51,280		$	2.85	$	186,659

Schedule of Accumulated Other Comprehensive Income Loss

The following table shows a summary of changes in accumulated other comprehensive income by component for the six months ended June 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		16,989			19			17,008
Amounts reclassified from accumulated other    comprehensive income (loss)		—			—			—
Net current-period other comprehensive income (loss)		16,989			19			17,008
Balance as of June 30, 2017	$	(111,682	)	$	(4	)	$	(111,686	)