Equity Incentive Plans (Tables)

12 Months Ended

Jan. 31, 2019

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

Summary of Stock Option Activity Under Equity Incentive Plans and Related Information

A summary of the stock option activity under our equity incentive plans and related information is as follows:

	Options Outstanding
	Number of Shares		Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Life (Years)	Aggregate Intrinsic Value (in thousands)
Balance as of January 31, 2018	46,359,949		$	7.75	6.3	$	574,224
Options exercised	(9,397,220	)	5.08
Options forfeited/canceled	(1,497,186	)	10.55
Balance as of January 31, 2019	35,465,543		$	8.34	5.4	$	339,591
Vested and exercisable as of January 31, 2019	26,592,658		$	6.76	5.1	$	296,710

Summary of Estimate Fair Value of Employee Stock Options and Employee Purchase Plan

We estimate the fair value of employee stock options and ESPP purchase rights using a Black-Scholes option pricing model with the following assumptions:

	Year Ended January 31,
	2017		2018		2019
Employee Stock Options
Expected term (in years)	6.1		6.1		n/a
Expected volatility	44	%	47	%	n/a
Risk-free interest rate	1.3% - 1.5%		1.9	%	n/a
Dividend rate	—		—		n/a
Fair value of common stock	$10.37 - $14.52		$12.84		n/a
Employee Stock Purchase Plan
Expected term (in years)	0.5 - 2.0		0.5 - 2.0		0.5 - 2.0
Expected volatility	41	%	35% - 39%		44% - 47%
Risk-free interest rate	0.5% - 0.9%		0.9% - 1.4%		2.0% - 2.8%
Dividend rate	—		—		—
Fair value of common stock	$12.36 - $13.72		$10.39 - $14.65		$20.62 - $27.66

Schedule of Share-based Compensation, Restricted Stock Units Award Activity

A summary of the RSU activity under our 2015 Plan and related information is as follows:

	Number of RSUs Outstanding		Weighted-Average Grant Date Fair Value		Aggregate Intrinsic Value (in thousands)
Unvested balance as of January 31, 2018	17,682,646		$	12.60	$	356,117
Granted	15,891,112		20.73
Vested	(8,403,422	)	13.24
Forfeited	(2,109,948	)	16.09
Converted	(1,142,838	)	11.86
Unvested balance of January 31, 2019	21,917,550		$	17.94	$	392,515

A summary of the restricted stock activity under our 2015 Plan and related information is as follows:

	Number of Restricted Stock Outstanding		Weighted- Average Grant Date Fair Value		Aggregate Intrinsic Value (in thousands)
Unvested Balance as of January 31, 2018	—		$	—	$	—
Granted and converted	3,514,020		19.25
Vested	(145,232	)	12.84
Forfeited/canceled	(1,101,219	)	21.15
Unvested Balance as of January 31, 2019	2,267,569		$	18.70	$	40,612

Summarizes the Components of Stock-Based Compensation

The following table summarizes the components of stock-based compensation expense recognized in the consolidated statements of operations (in thousands):

	Year Ended January 31,
	2017		2018		2019
Cost of revenue—product	$	601	$	1,630	$	2,951
Cost of revenue—support subscription	5,639		9,050		12,378
Research and development	63,495		71,229		92,484
Sales and marketing	34,317		47,687		66,350
General and administrative	12,616		21,077		36,482
Total stock-based compensation expense	$	116,668	$	150,673	$	210,645