Stock Option Plans (Tables)

12 Months Ended

Jan. 31, 2020

Share-based Payment Arrangement [Abstract]

Schedule of Stock Option Activity

The following table summarizes stock option activity and related information under the Stock Plans:

	Options Outstanding
	Options Outstanding	Weighted- Average Exercise Price		Weighted-Average Remaining Contractual Term (Years)	Aggregate Intrinsic Value (in thousands)
Balance — January 31, 2019	19,117,696	$	5.83	4.3	$	154,431
Exercised	(4,395,673)	2.88		—	—
Canceled	(1,191,660)	15.25		—	—
Balance — January 31, 2020	13,530,363	$	5.96	2.1	$	70,057
Exercisable— January 31, 2020	13,478,227	$	5.91	2.0	$	70,057
Vested and Expected to Vest — January 31, 2020	13,530,363	$	5.96	2.1	$	70,057

Schedule of Weighted Average Assumptions in Calculating Option Fair Value

The fair value of each stock option grant was estimated at the grant date using the Black-Scholes option-pricing model with the following weighted-average assumptions:

	Years Ended January 31,
		2019	2018
Volatility		45.0%	45.3%
Risk-free interest rate		2.5%	2.0%
Expected term (in years)		5.0 years	6.1 years
Expected dividends		—%	—%

Schedule of Restricted Stock Activity

The following table summarizes RSU activity and related information under the Stock Plans:

	RSUs Outstanding
	Number of RSUs	Weighted-Average Grant Date Fair Value Per Share
Balance —January 31, 2019	35,058,103	$	13.25
Granted	36,075,434	8.96
Canceled	(9,276,310)	12.49
Vested and converted to shares	(23,273,233)	11.15
Balance —January 31, 2020	38,583,994	$	10.85

Schedule of Share-based Payment Award, Employee Stock Purchase Plan, Valuation Assumptions

The fair value of each ESPP grant was estimated at the grant date using the Black-Scholes option-pricing model with the following weighted-average assumptions:

	Years Ended January 31,
	2020	2019	2018
Volatility	31.9%	38.8%	32.9%
Risk-free interest rate	1.9%	2.4%	1.2%
Expected term (in years)	0.5 years	0.5 years	0.6 years
Expected dividends	—%	—%	—%