Equity Award Plan Activities (Tables)

9 Months Ended

Sep. 30, 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	82		244.20
Options exercised	(1,038	)	33.07
Options canceled	(41	)	53.44
Balance—September 30, 2018	6,027		$	35.78	5.4	$	1,386,807
Vested and exercisable—September 30, 2018	2,734		$	22.39	4.8	$	665,576

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	231		274.46
RSUs vested	(405	)	93.92
RSUs forfeited/canceled	(56	)	127.57
Unvested balance—September 30, 2018	1,307		$	136.63	1.5	$	347,386

Schedule of Shares Available for Grant

The following table presents the stock activity and the total number of shares available for grant under the 2014 Plan as of September 30, 2018 (in thousands):

	Number of Shares
Balance—December 31, 2017	13,512
Authorized	2,211
Options granted	(82	)
RSUs granted	(231	)
Options canceled	41
RSUs forfeited	56
Shares traded for taxes	27
Balance—September 30, 2018	15,534

Schedule of Stock-Based Compensation Expense

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

	Three Months Ended September 30,				Nine Months Ended   September 30,
	2018		2017		2018		2017
Cost of revenue	$	1,268	$	1,113	$	3,706	$	3,224
Research and development	12,010		11,048		34,700		30,977
Sales and marketing	6,537		5,115		18,771		12,651
General and administrative	3,439		2,876		9,406		8,139
Total stock-based compensation	$	23,254	$	20,152	$	66,583	$	54,991

Schedule of Unrecognized Stock-Based Compensation Expense

As of September 30, 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).

	September 30, 2018
	Stock Option		RSU		ESPP		Restricted Stock
Unrecognized stock-based compensation expense	$	60,754	$	161,733	$	9,722	$	5,825
Weighted-average amortization period	3.6 years		3.2 years		1.2 years		4.0 years