Stock-Based Compensation (Tables)

9 Months Ended

Oct. 31, 2018

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, 2018		10,843,120		$	8.32		5.74	$	150,922
Options granted		717,658			20.78
Options exercised		(1,745,370	)		8.58
Options forfeited/cancelled		(461,801	)		14.10
Balance as of October 31, 2018		9,353,607		$	8.94		5.20	$	87,143
Vested and expected to vest as of October 31, 2018		9,281,847		$	8.87		5.17	$	87,071
Exercisable as of October 31, 2018		7,788,714		$	7.04		4.50	$	85,578

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, 2018		14,619,252		$	16.42
Granted		9,298,770			22.58
Vested, net of shares withheld for employee payroll taxes		(2,656,081	)		16.51
Forfeited/cancelled		(2,922,723	)		17.41
Unvested balance - October 31, 2018		18,339,218		$	19.38

Summary of Components of Stock-Based Compensation Expense

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

	Three Months Ended				Nine Months Ended
	October 31,				October 31,
	2018		2017		2018		2017
Cost of revenue	$	3,598	$	2,814	$	10,280	$	7,945
Research and development		12,043		9,705		33,668		28,419
Sales and marketing		9,708		8,208		27,701		23,882
General and administrative		6,441		4,796		17,437		12,290
Total stock-based compensation	$	31,790	$	25,523	$	89,086	$	72,536

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,
	2018					2017					2018					2017
Employee Stock Options
Expected term (in years)					5.8					6.1		5.5	-		5.8		5.5	-		6.1
Risk-free interest rate				3.1%					2.0%		2.8%		-	3.1%		1.8%		-	2.1%
Volatility				45%					39%					45%		38%		-	40%
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	2.3%		-	2.8%		1.2%		-	1.4%		2.0%		-	2.8%		0.9%		-	1.4%
Volatility	40%		-	48%		29%		-	40%		37%		-	50%		28%		-	43%
Dividend yield				0%					0%					0%					0%