Equity Incentive Plans - Stock Option Activity (Details) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2021 USD ($) $ / shares shares	Dec. 31, 2020 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Beginning balance (in shares) | shares	19,600,223,000
Options granted (in shares) | shares	610,534,000
Options assumed upon acquisition (in shares) | shares	23,494,000
Options exercised (in shares) | shares	(4,941,362,000)
Options cancelled and forfeited (in shares) | shares	(386,010,000)
Ending balance (in shares) | shares	14,906,879,000	19,600,223,000
Stock Options Weighted Average Exercise Price Per Share
Options outstanding, Weighted average exercise price per share (in dollars per share) | $ / shares	$ 4.27
Options granted, Weighted average exercise price per share (in dollars per share) | $ / shares	105.37
Options assumed upon acquisition, Weighted average exercise price per share (in dollars per share) | $ / shares	9.06
Options exercised, Weighted average exercise price per share (in dollars per share) | $ / shares	1.98
Options forfeited or expired, Weighted average exercise price per share (in dollars per share) | $ / shares	7.30
Options outstanding, Weighted average exercise price per share (in dollars per share) | $ / shares	$ 9.10	$ 4.27
Stock Option Activity, Additional Disclosures
Options outstanding, Weighted average remaining contractual term	6 years 8 months 12 days	6 years 9 months 18 days
Options outstanding, Aggregate intrinsic value (in dollars) | $	$ 4,581,564	$ 715,084
Options exercisable, Number of options | shares	8,598,833,000
Options exercisable, Weighted average exercise price per share (in dollars per share) | $ / shares	$ 2.48
Options exercisable, Weighted average remaining contractual term	5 years 3 months 18 days
Options exercisable, Aggregate intrinsic value (in dollars) | $	$ 2,699,739
Options vested and expected to vest (in shares) | shares	14,753,486,000
Options vested and expected to vest, Weighted Average Exercise Price Per Share (in dollars per share) | $ / shares	$ 8.78
Options vested and expected to vest, Weighted average remaining contractual term	6 years 7 months 6 days
Options vested and expected to vest, Aggregate intrinsic value (in dollars) | $	$ 4,539,113