Stock-Based Compensation (Tables)

9 Months Ended

Oct. 31, 2017

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

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

The following table summarizes the stock option activity under the equity incentive plans and related information:

	SharesSubject to Options Outstanding					Weighted-Average
				Weighted-		Remaining
				Average Exercise		Contractual Life		Aggregate
	Shares			Price		(Years)		Intrinsic Value
								(in thousands)
Balance as of January 31, 2017		12,318,800		$	7.44		6.42	$	119,606
Options granted		1,533,056			17.46
Option exercised		(1,561,172	)		6.36
Options forfeited/cancelled		(852,990	)		15.05
Balance as of October 31, 2017		11,437,694		$	8.37		5.99	$	155,364
Vested and expected to vest as of October 31, 2017		11,330,158		$	8.30		5.97	$	154,675
Exercisable as of October 31, 2017		8,939,286		$	6.36		5.30	$	139,342

Summary of Restricted Stock Unit Activity Under Equity Incentive Plans and Related Information

The following table summarizes the restricted stock unit activity under the equity incentive plans and related information:

	Number of			Weighted-
	Restricted			Average
	Stock Units			Grant Date
	Outstanding			Fair Value
Unvested balance - January 31, 2017		11,822,316		$	14.67
Granted		6,820,260			17.74
Vested, net of shares withheld for employee    payroll taxes		(2,338,184	)		14.51
Forfeited/cancelled		(1,342,417	)		15.12
Unvested balance - October 31, 2017		14,961,975		$	16.22

Summary of Components of Stock-Based Compensation Expense

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

	Three Months Ended				Nine Months Ended
	October 31,				October 31,
	2017		2016		2017		2016
Cost of revenue	$	2,814	$	1,986	$	7,945	$	5,328
Research and development		9,705		7,730		28,419		21,602
Sales and marketing		8,208		6,744		23,882		18,390
General and administrative		4,796		3,457		12,290		9,750
Total stock-based compensation	$	25,523	$	19,917	$	72,536	$	55,070

Summary of Estimated Fair Value of Employee Stock Options

We estimated the fair value of employee stock options and 2015 ESPP purchase rights using a Black-Scholes option pricing model with the following assumptions:

	Three Months Ended										Nine Months Ended
	October 31,										October 31,
	2017					2016					2017					2016
Employee Stock Options
Expected term (in years)					6.1					6.0		5.5		-	6.1		5.5		-	6.0
Risk-free interest rate					2.0%		1.3	%	-	1.4%		1.8	%	-	2.1%		1.3	%	-	1.5%
Volatility					39%					40%		38	%	-	40%		40	%	-	43%
Dividend yield					0%					0%					0%					0%
Employee Stock Purchase Plan
Expected term (in years)		0.5		-	2.0		0.5		-	2.0		0.5		-	2.0	0.5			-	2.0
Risk-free interest rate		1.2	%	-	1.4%		0.5	%	-	0.8%		0.9	%	-	1.4%		0.5	%	-	0.9%
Volatility		29	%	-	40%		39	%	-	51%		28	%	-	43%		39	%	-	60%
Dividend yield					0%					0%					0%					0%