Stock-Based Compensation (Tables)

6 Months Ended

Jul. 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		697,686			20.84
Option exercised		(1,446,438	)		8.87
Options forfeited/cancelled		(408,689	)		13.93
Balance as of July 31, 2018		9,685,679		$	8.90		5.44	$	146,041
Vested and expected to vest as of July 31, 2018		9,601,241		$	8.82		5.41	$	145,527
Exercisable as of July 31, 2018		7,817,955		$	6.73		4.66	$	134,679

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		6,968,238			22.26
Vested, net of shares withheld for employee payroll taxes		(1,786,786	)		16.30
Forfeited/cancelled		(1,940,121	)		16.97
Unvested balance - July 31, 2018		17,860,583		$	18.65

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				Six Months Ended
	July 31,				July 31,
	2018		2017		2018		2017
Cost of revenue	$	3,561	$	2,663	$	6,682	$	5,131
Research and development		11,477		9,554		21,625		18,714
Sales and marketing		9,932		7,934		17,993		15,674
General and administrative		5,713		3,916		10,996		7,494
Total stock-based compensation	$	30,683	$	24,067	$	57,296	$	47,013

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										Six Months Ended
	July 31,										July 31,
	2018					2017					2018					2017
Employee Stock Options
Expected term (in years)		5.5	-		5.8		5.5	-		6.0		5.5	-		5.8		5.5	-		6.0
Risk-free interest rate	2.2%		-	2.3%		1.8%		-	2.0%		2.2%		-	2.3%		1.8%		-	2.4%
Volatility	45%		-	45%		38%		-	39%		45%		-	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	2.0%		-	2.3%		0.9%		-	1.4%		2.0%		-	2.3%		0.9%		-	1.4%
Volatility	37%		-	50%		28%		-	43%		37%		-	50%		28%		-	43%
Dividend yield				0%					0%					0%					0%