Net Loss per Share Attributable to Common Stockholders - Common Stock Equivalents Excluded from Calculation of Diluted Net Loss Per Share (Details) - shares	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020
Class A Common Stock [Member]
Earnings Per Share Basic [Line Items]
Outstanding stock options	90,038,538	18,116,302	0
Class A Common Stock [Member] | Stock Option Activity [Member]
Earnings Per Share Basic [Line Items]
Outstanding stock options	73,609,565	18,116,302	0
Class A Common Stock [Member] | Redeemable Convertible Preferred Stock [Member]
Earnings Per Share Basic [Line Items]
Outstanding stock options	0	0	0
Class A Common Stock [Member] | Issuance Of Common Stock Upon Early Exercise Of Options Unvested [Member]
Earnings Per Share Basic [Line Items]
Outstanding stock options	0	0	0
Class A Common Stock [Member] | Restricted Stock Units [Member]
Earnings Per Share Basic [Line Items]
Outstanding stock options	10,676,378	0	0
Class A Common Stock [Member] | Shares subject to vesting [Member]
Earnings Per Share Basic [Line Items]
Outstanding stock options	3,512,839	0	0
Class A Common Stock [Member] | Employee Stock Purchase Plan [Member]
Earnings Per Share Basic [Line Items]
Outstanding stock options	2,239,756	0	0
Class B Common Stock [Member]
Earnings Per Share Basic [Line Items]
Outstanding stock options	0	258,442,958	275,407,375
Class B Common Stock [Member] | Stock Option Activity [Member]
Earnings Per Share Basic [Line Items]
Outstanding stock options	0	49,261,103	68,392,497
Class B Common Stock [Member] | Redeemable Convertible Preferred Stock [Member]
Earnings Per Share Basic [Line Items]
Outstanding stock options	0	209,181,855	198,274,933
Class B Common Stock [Member] | Issuance Of Common Stock Upon Early Exercise Of Options Unvested [Member]
Earnings Per Share Basic [Line Items]
Outstanding stock options	0	0	8,739,945
Class B Common Stock [Member] | Restricted Stock Units [Member]
Earnings Per Share Basic [Line Items]
Outstanding stock options	0	0	0
Class B Common Stock [Member] | Shares subject to vesting [Member]
Earnings Per Share Basic [Line Items]
Outstanding stock options	0	0	0
Class B Common Stock [Member] | Employee Stock Purchase Plan [Member]
Earnings Per Share Basic [Line Items]
Outstanding stock options	0	0	0