Stock-based Compensation (Tables)

9 Months Ended

Oct. 31, 2021

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Classification of Stock-based Compensation

The following table presents the classification of stock-based compensation for the periods indicated:

	Three Months Ended October 31,				Nine Months Ended October 31,
	2021		2020		2021		2020
	(in thousands)
Stock-based compensation:
Cost of revenue	$	391	$	368	$	1,073	$	981
Research and development		13,725		11,496		36,444		31,402
Selling, general and administrative		7,937		7,113		22,750		19,024
Total stock-based compensation	$	22,053	$	18,977	$	60,267	$	51,407

Weighted-Average Assumptions Used to Estimate Fair Value

The following table sets forth the weighted-average assumptions used to estimate the fair value of stock options and employee stock purchase plan awards for the periods indicated:

	Three Months Ended October 31,						Nine Months Ended October 31,
	2021			2020			2021			2020
Stock Options:
Volatility		—			52	%		51	%		52	%
Risk-free interest rate		—			0.40	%		0.98	%		0.52	%
Expected term (years)		—		5.81			5.27			5.84
Dividend yield		—			0	%		0	%		0	%
Employee stock purchase plan awards:
Volatility		54	%		58	%		57	%		59	%
Risk-free interest rate		0.05	%		0.12	%		0.06	%		0.21	%
Expected term (years)	0.5			0.5			0.5			0.5
Dividend yield		0	%		0	%		0	%		0	%

Stock Option Activities

The following table summarizes stock option activities for the period indicated:

	Option Outstanding
										Weighted-
								Total Intrinsic		Average
						Weighted-		Value Of		Remaining		Aggregate
				Weighted-		Average		Options		Contractual		Intrinsic
				Average		Grant-date		Exercised		Term		Value
	Shares			Exercise Price		Fair Value		(in thousands)		(in years)		(in thousands)
Outstanding at January 31, 2021		719,143		$	38.33
Granted		14,700			110.19	$	50.28
Exercised		(229,051	)		25.37			$	19,201
Forfeited		(7,401	)		69.40
Expired		(1,146	)		9.86
Outstanding at October 31, 2021		496,245			46.05					4.64		$	69,365
Exercisable at October 31, 2021		411,465		$	42.64						3.90	$	58,916

Restricted Stock Units Activities

The following table summarizes restricted stock units activities for the period indicated:

				Weighted-
				Average
				Grant-Date
	Shares			Fair Value
Unvested at January 31, 2021		2,871,801		$	51.73
Granted		1,113,417			122.39
Vested		(1,029,869	)		50.81
Forfeited		(48,983	)		66.60
Unvested at October 31, 2021		2,906,366		$	78.88