Equity Award Plan Activities (Tables)

3 Months Ended

Mar. 31, 2019

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, 2018	5,899		$	37.09	5.2	$	1,027,741
Options granted	74		225.25
Options exercised	(613	)	28.71
Options canceled	(8	)	35.06
Balance—March 31, 2019	5,352		$	40.64	5.1	$	1,465,345
Vested and exercisable—March 31, 2019	2,762		$	26.11	4.5	$	796,325

Schedule of Restricted Stock Units Activity

A summary of the RSU activity under our 2014 equity incentive plan (“2014 Plan”) 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, 2018	1,308		$	150.60	1.5	$	275,638
RSUs granted	41		226.29
RSUs vested	(132	)	111.39
RSUs forfeited/canceled	(18	)	175.69
Unvested balance—March 31, 2019	1,199		$	157.14	1.5	$	376,948

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 March 31, 2019 (in thousands):

	Number of Shares
Balance—December 31, 2018	15,386
Options granted	(74	)
RSUs granted	(41	)
Options canceled	8
RSUs forfeited	18
Shares traded for taxes	6
Balance—March 31, 2019	15,303

Schedule of Stock-Based Compensation Expense

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

	Three Months Ended March 31,
	2019		2018
Cost of revenue	$	1,098	$	1,202
Research and development	13,131		10,945
Sales and marketing	6,534		5,960
General and administrative	3,528		2,744
Total stock-based compensation	$	24,291	$	20,851

Schedule of Unrecognized Stock-Based Compensation Expense

As of March 31, 2019, 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, 2019
	Stock Option		RSU		ESPP		Restricted Stock
Unrecognized stock-based compensation expense	$	58,501	$	167,360	$	6,871	$	5,028
Weighted-average amortization period	3.8 years		3.2 years		1.0 years		3.5 years