Common Stock (Tables)

12 Months Ended

Jan. 31, 2018

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Summary of Reserved Shares of Authorized but Unissued Common Stock

As of January 31, 2017 and 2018, the Company had reserved the following shares of authorized but unissued common stock:

	As of January 31,
	2017		2018
	(in shares)
Convertible preferred stock		10,610,966		—
Options and RSUs outstanding and shares available for grant		5,814,388		12,080,540
Convertible preferred stock warrants		40,250		—
Common stock warrants		25,000		1,897,562
Total		16,490,604		13,978,102

Schedule of Weighted-Average Assumptions Used to Estimate Fair Value of Stock Options Granted

The weighted-average assumptions used to estimate the fair value of stock options granted in the following periods was:

	Year Ended January 31,
	2016			2017			2018
Risk-free interest rate		1.64	%		1.52	%		1.86	%
Expected term (in years)		6.08			6.04			5.47
Expected volatility		55.80	%		61.68	%		48.21	%
Dividend yield		—			—			—

Summary of Restricted Stock Unit Activity

The following is a summary of RSU activity under the Company’s stock plans for the year ended January 31, 2018, is presented below:

	Shares			Weighted average grant date fair value per share
Outstanding—January 31, 2016		—		$	—
Awarded		319,885		$	30.54
Released		—		$	—
Forfeited		(34,050	)	$	30.06
Outstanding—January 31, 2017		285,835		$	30.60
Awarded		7,157,672		$	9.23
Released		—		$	—
Forfeited		(724,213	)	$	13.33
Outstanding—January 31, 2018		6,719,294		$	9.69

Schedule of Total Stock-Based Compensation Expense Recognized by Type of Award

Total stock-based compensation expense recognized for stock award in the consolidated statements of operations and by type of award is as follows (in thousands):

	Year Ended January 31,
	2016		2017		2018
Stock-based compensation:
Cost of product revenue	$	181	$	264	$	1,612
Cost of support and maintenance revenue		176		323		1,579
Research and development		2,906		5,227		21,608
Sales and marketing		3,073		4,115		10,432
General and administrative		3,419		3,905		16,587
Total stock-based compensation expense(1)	$	9,755	$	13,834	$	51,818

	Year Ended January 31,
	2016		2017		2018
Stock-based compensation:
Stock options(1) (2)	$	9,755	$	13,834	$	19,821
RSUs(1)		—		—		30,984
ESPP		—		—		1,013
Total stock-based compensation expense	$	9,755	$	13,834	$	51,818

⁽¹⁾ In September 2017, the Company’s board of directors approved a restructuring plan (Note 12), which resulted in a $0.7 million non-cash adjustment to restructuring charges for previously recognized stock-based compensation expense related to awards that will not vest as a result of the restructuring plan.

⁽²⁾ In May 2017, the Company repriced each outstanding and unexercised stock option held by current service providers with an exercise price in excess of $13.68 per share (each, an Eligible Option), to a new exercise price of $13.68 per share, which is no less than the fair market value of the Company's common stock as determined by the Company's compensation committee on the date of repricing. Eligible Options covering 3,291,783 shares of the Company's common stock with a weighted average exercise price of $24.31 were repriced. Additional stock-based compensation expense related to this repricing is $7.3 million, of which $2.6 million was recognized immediately on the date of repricing for Eligible Options that were vested.

2017 Employee Stock Purchase Plan

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Schedule of Black-Scholes Option-pricing Model to Determine Fair Value of Shares Purchased under ESPP with Weighted Average Assumptions on Date of Grant

The Company uses the Black-Scholes option-pricing model to determine the fair value of shares purchased under the ESPP with the following weighted average assumptions on the date of the grant:

	Year Ended January 31,
	2016	2017	2018
Risk-free interest rate	n/a	n/a		1.32	%
Expected term (in years)	n/a	n/a		1.36
Expected volatility	n/a	n/a		45.74	%
Dividend yield	n/a	n/a		—

2008 Stock Plan

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Summary of Shares Available for Grant under Stock Plans

The following is a summary of shares available for grant under the Company’s stock plans for the years ended January 31, 2017 and 2018:

Available for grant—January 31, 2016	156,417
Authorized	1,405,316
Options and RSUs granted	(1,240,032	)
Options and RSUs canceled	738,891
Available for grant—January 31, 2017	1,060,592
Authorized	7,024,194
Options and RSUs granted	(8,738,088	)
Options and RSUs canceled	1,661,703
Available for grant—January 31, 2018	1,008,401

Summary of Stock Option Activity

The following is a summary of stock option activity under the Company’s stock plans for the years ended January 31, 2017 and 2018:

				Options Outstanding
	Number of shares underlying outstanding options			Weighted- average exercise price		Weighted- average remaining contractual term		Aggregate Intrinsic Value
						(in years)		(in thousands)
Outstanding—January 31, 2017		4,467,961		$	18.83		7.5	$	60,756
Options granted		1,580,416		$	16.72
Options exercised		(219,896	)	$	10.04
Options canceled		(1,475,636	)	$	12.88
Outstanding—January 31, 2018		4,352,845		$	12.49		7.2	$	756
Vested and exercisable
January 31, 2018		2,908,420		$	12.19		6.7	$	692
Vested and Expected to Vest
January 31, 2018		4,352,845		$	12.49		7.2	$	756