Stockholders' Equity - Summary of Stock Option Activity (Detail) $ / shares in Units, $ in Millions	9 Months Ended	12 Months Ended
	Oct. 31, 2021 USD ($) $ / shares shares	Jan. 31, 2021 USD ($) $ / shares shares
Number of shares
Options outstanding, Beginning balance (in shares) | shares	12,761,289
Options granted (in shares) | shares	1,081,518
Options exercised (in shares) | shares	(1,074,939)
Options forfeited/cancelled (in shares) | shares	(267,795)
Options outstanding, Ending balance (in shares) | shares	12,500,073	12,761,289
Options vested and exercisable (in shares) | shares	7,197,020
Options vested and exercisable and expected to vest thereafter (in shares) | shares	12,500,073
Weighted average exercise price
Options outstanding, Beginning balance (in usd per share) | $ / shares	$ 57.48
Options granted (in usd per share) | $ / shares	278.07
Options exercised (in usd per share) | $ / shares	40.29
Options forfeited/cancelled (in usd per share) | $ / shares	166.28
Options outstanding, Ending balance (in usd per share) | $ / shares	75.71	$ 57.48
Options vested and exercisable (in usd per share) | $ / shares	28.82
Options vested and exercisable and expected to vest thereafter (in usd per share) | $ / shares	$ 75.71
Weighted average remaining contractual term (in years), Options outstanding	4 years 9 months 18 days	5 years
Weighted average remaining contractual term (in years), Options vested and exercisable	2 years 9 months 18 days
Weighted average remaining contractual term (in years), Options vested and exercisable and expected to vest thereafter	4 years 9 months 18 days
Aggregate intrinsic value (in millions)
Options outstanding | $	$ 3,016	$ 2,794
Options vested and exercisable | $	2,074
Options vested and exercisable and expected to vest thereafter | $	$ 3,016