Employee Benefits and Stock-based Compensation (Tables)

12 Months Ended

Jan. 31, 2023

Postemployment Benefits [Abstract]

Classification of Stock-based Compensation

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

	Year Ended January 31,
	2023		2022		2021
	(in thousands)
Stock-based compensation:
Cost of revenue	$	3,597	$	1,489	$	1,328
Research and development		71,236		54,787		42,903
Selling, general and administrative		36,325		31,525		25,903
Total stock-based compensation	$	111,158	$	87,801	$	70,134

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:

	Year Ended January 31,
	2023			2022			2021
Stock Options:
Volatility		—			51	%		52	%
Risk-free interest rate		—			1.04	%		0.52	%
Expected term (years)		—			5.06			5.78
Dividend yield		—			0	%		0	%
Employee stock purchase plan awards:
Volatility		81	%		57	%		59	%
Risk-free interest rate		2.32	%		0.06	%		0.21	%
Expected term (years)		0.5			0.5			0.5
Dividend yield		0	%		0	%		0	%

Stock Option Activities

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

	Option Outstanding
												Weighted-
										Total Intrinsic		Average
						Weighted-		Weighted-		Value of		Remaining	Aggregate
				Weighted-		Average		Average		options		Contractual	Intrinsic
				Average		Grant-date		Acquisition-date		Exercised		Term	Value
	Shares			Exercise Price		Fair Value		Fair Value		(in thousands)		(in years)	(in thousands)
Outstanding at January 31, 2020		1,124,646		$	32.93
Granted		51,200			59.54	$	28.37
Exercised		(421,736	)		24.52					$	19,401
Forfeited		(11,618	)		46.69
Expired		(23,349	)		70.11
Outstanding at January 31, 2021		719,143			38.33
Granted		14,700			110.19	$	50.28
Assumed		163,581			23.10			$	173.04
Exercised		(269,287	)		28.23					$	25,622
Forfeited		(7,669	)		68.95
Expired		(1,146	)		9.86
Outstanding at January 31, 2022		619,322			40.08
Exercised		(121,624	)		30.34					$	6,712
Forfeited		(10,618	)		55.97
Expired		(2,289	)		39.19
Outstanding at January 31, 2023		484,791			42.18							4.38	$	23,346
Exercisable at January 31, 2023		370,158		$	44.47							3.59	$	16,927

Restricted Stock Unit Activities

The following table summarizes restricted stock unit activities for the periods indicated:

				Weighted-
				Average
				Grant-Date
	Shares			Fair Value
Unvested at January 31, 2020		2,617,266		$	50.30
Granted		1,499,203			53.45
Vested		(1,162,883	)		50.53
Forfeited		(81,785	)		54.48
Unvested at January 31, 2021		2,871,801			51.73
Granted		1,213,257			128.80
Vested		(1,367,309	)		53.85
Forfeited		(66,614	)		71.59
Unvested at January 31, 2022		2,651,135			85.41
Granted		1,549,174			74.45
Vested		(1,513,972	)		71.32
Forfeited		(112,978	)		99.46
Unvested at January 31, 2023		2,573,359		$	86.81