Equity Incentive Plans (Tables)

12 Months Ended

Jan. 31, 2017

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

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

A summary of 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, 2016	68,879,087		$	6.43	7.9	$	505,131
Options granted	1,999,000		12.69
Options exercised	(10,180,258	)	1.47
Options cancelled/forfeited	(3,857,640	)	12.18
Balance as of January 31, 2017	56,840,189		$	7.15	7.0	$	315,502
Vested and exercisable as of January 31, 2017	29,575,922		$	4.12	6.2	$	228,436

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,
	2015	2016		2017
Employee Stock Options
Expected term (in years)	5.0 - 6.9	6.0 - 7.4		6.1
Expected volatility	55% - 68%	48% - 52%		44	%
Risk-free interest rate	1.3% - 2.2%	1.5% - 1.9%		1.25% - 1.49%
Dividend rate	—	—		—
Fair value of common stock	$4.81 - $12.65	$13.94 - $19.68		$10.37 - $14.52
Employee Stock Purchase Plan
Expected term (in years)	—	0.4 - 1.9		0.5 - 2.0
Expected volatility	—	49	%	41	%
Risk-free interest rate	—	0.1% - 0.7%		0.5% - 0.9%
Dividend rate	—	—		—

Summary of Estimate Fair Value of Non-employee Stock

We estimate the fair value of non-employee stock options on the date of grant using a Black-Scholes option pricing model with the following assumptions:

	Year Ended January 31,
	2015	2016			2017
Expected term (in years)	10.0	10.0			—
Expected volatility	62% - 63%	49		%	—
Risk-free interest rate	1.6% - 2.6%	1.5		%	—
Dividend rate	—	—			—
Fair value of common stock	$9.40 - $12.40		$17.00		—

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

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

	Number of Restricted Stock Units Outstanding	Weighted-Average Grant Date Fair value		Aggregate Intrinsic Value
				(in thousands)
Unvested Balance as of January 31, 2016	53,000	$	16.98	$	690
Granted	10,501,600	13.15
Vested	(1,237,502)	13.95
Forfeited	(534,074)	13.16
Unvested Balance of January 31,2017	8,783,024	$	13.06	$	99,863

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,
	2015		2016		2017
Cost of revenue—product	$	303	$	276	$	601
Cost of revenue—support	1,273		2,388		5,639
Research and development	22,512		31,135		63,495
Sales and marketing	22,466		16,966		34,317
General and administrative	6,479		7,460		12,616
Total stock-based compensation expense	$	53,033	$	58,225	$	116,668