Stock Incentive Plans - Summary of Stock Option Activity Under Stock Incentive Plan (Details) - Stock Options - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Number of Options
Balance at the beginning of the period (in shares)	23,421,374	25,159,411	19,628,032
Granted (in shares)	29,113,555	6,404,800	17,008,222
Exercised (in shares)	(4,277,344)	(6,084,183)	(8,529,478)
Canceled and forfeited (in shares)	(4,072,097)	(2,058,654)	(2,947,365)
Balance at the end of the period (in shares)	44,185,488	23,421,374	25,159,411	19,628,032
Weighted-Average Exercise Price per Share
Balance at the beginning of the period (in dollars per share)	$ 1.35	$ 0.92	$ 0.19
Granted (in dollars per share)	20.07	2.31	1.30
Exercised (in dollars per share)	1.18	0.53	0.13
Canceled and forfeited (in dollars per share)	5.58	1.50	0.54
Balance at the end of the period (in dollars per share)	$ 13.31	$ 1.35	$ 0.92	$ 0.19
Option Activity, Additional Disclosures
Options outstanding, Weighted Average Remaining Contractual Life (Years)	8 years 5 months 15 days	8 years 3 months 29 days	8 years 8 months 26 days	7 years 8 months 8 days
Options outstanding, Aggregate Intrinsic Value (in USD)	$ 279,242	$ 248,002	$ 46,594	$ 38,982
Options Vested as of June 30, 2021, Number of Options (in shares)	10,007,419
Options Vested as of June 30, 2021, Exercise Price per Share (in dollars per share)	$ 1.53
Options Vested, Weighted Average Remaining Contractual Life (Years)	6 years 8 months 1 day
Options Vested, as of June 30, 2021, Aggregate Intrinsic Value (in USD)	$ 157,032