Stock-Based Compensation (Tables)

3 Months Ended

Apr. 30, 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:

	Shares Subject 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		650,000			20.28
Option exercised		(631,210	)		6.92
Options forfeited/cancelled		(283,185	)		13.67
Balance as of April 30, 2018		10,578,725		$	9.00		5.73	$	146,660
Vested and expected to vest as of April 30, 2018		10,483,748		$	8.92		5.70	$	146,139
Exercisable as of April 30, 2018		8,425,468		$	6.85		4.95	$	134,858

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		5,211,663			20.98
Vested, net of shares withheld for employee payroll taxes		(1,010,888	)		15.91
Forfeited/cancelled		(838,952	)		16.18
Unvested balance - April 30, 2018		17,981,075		$	17.79

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
	April 30,
	2018		2017
Cost of revenue	$	3,121	$	2,468
Research and development		10,148		9,160
Sales and marketing		8,061		7,740
General and administrative		5,283		3,578
Total stock-based compensation	$	26,613	$	22,946

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 assumption. During the three months ended April 30, 2018, we had no stock option grants awarded using a Black-Scholes option pricing model.

	Three Months Ended
	April 30,
	2017
Employee Stock Options
Expected term (in years)					6.0
Risk-free interest rate		2.1	%	-	2.4	%
Volatility		39	%	-	40	%
Dividend yield					0	%


	Three Months Ended
	April 30,
Employee Stock Purchase Plan	2018						2017
Expected term (in years)		0.5		-	2.0			0.5		-	2.0
Risk-free interest rate		2.0	%	-	2.3	%		0.9	%	-	1.4	%
Volatility		37	%	-	50	%		28	%	-	43	%
Dividend yield					0	%					0	%