Equity Award Plan Activities (Tables)

3 Months Ended

Mar. 31, 2018

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

Schedule of Option Activity

The following table summarizes the option activity under our stock plans and related information (in thousands, except years and per share amounts):

	Options Outstanding
	Number of Shares Underlying Outstanding Options		Weighted- Average Exercise Price per Share		Weighted- Average Remaining Contractual Term (Years) of Stock Options	Aggregate Intrinsic Value of Stock Options Outstanding
Balance—December 31, 2017	7,024		$	33.05	6.1	$	1,422,637
Options granted	—		—
Options exercised	(394	)	25.39
Options canceled	(18	)	41.58
Balance—March 31, 2018	6,612		$	33.48	5.9	$	1,466,783
Vested and exercisable—March 31, 2018	2,911		$	22.71	5.3	$	676,982

Schedule of Restricted Stock Units Activity

A summary of the RSU activity under our stock plans and related information are presented below (in thousands, except years and per share amounts):

	Number of Shares		Weighted- Average Grant Date Fair Value Per Share		Weighted-Average Remaining Contractual Term (in years)	Aggregate Intrinsic Value
Unvested balance—December 31, 2017	1,537		$	104.29	1.6	$	362,119
RSUs granted	153		279.87
RSUs vested	(136	)	87.07
RSUs forfeited/canceled	(25	)	121.92
Unvested balance—March 31, 2018	1,529		$	123.10	1.6	$	390,315

Schedule of Shares Available for Grant

The following table presents the stock activity and the total number of shares available for grant as of March 31, 2018 (in thousands):

	Number of Shares
Balance—December 31, 2017	13,512
Authorized	2,211
RSUs granted	(153	)
Options canceled	18
RSUs forfeited	25
Shares traded for taxes	7
Balance—March 31, 2018	15,620

Schedule of Stock-Based Compensation Expense

Total stock-based compensation expense related to options, restricted stock awards, restricted stock units and employee stock purchase rights granted were allocated as follows (in thousands):

	Three Months Ended March 31,
	2018		2017
Cost of revenue	$	1,202	$	1,024
Research and development	10,945		9,587
Sales and marketing	5,960		3,456
General and administrative	2,744		2,372
Total stock-based compensation	$	20,851	$	16,439

Schedule of Unrecognized Stock-Based Compensation Expense

As of March 31, 2018, unrecognized stock-based compensation expenses by award type and their expected weighted-average recognition periods are summarized in the following table (in thousands, except years).

	March 31, 2018
	Stock Option		RSU		ESPP
Unrecognized stock-based compensation expense	$	61,271	$	174,249	$	4,996
Weighted-average amortization period	3.5 years		3.5 years		1.1 years