Share-Based Compensation - Summary of Stock Option Activity (Details) - USD ($)	3 Months Ended	9 Months Ended
	Mar. 31, 2021	Sep. 30, 2021	Sep. 30, 2020
Options Outstanding
Beginning balance (in shares)	25,087,416	25,087,416
Granted (in shares)		9,377,000
Exercised (in shares)		(5,589,084)
Expired (in shares)		(2,891,509)
Forfeited (in shares)		(3,067,750)
Ending balance (in shares)		22,916,073
Vested at end of period (in shares)		12,369,305
Expected to vest at end of period (in shares)		10,546,768
Weighted Average Exercise Price
Beginning balance (in dollars per share)	$ 1.29	$ 1.29
Granted (in dollars per share)		2.50
Exercised (in dollars per share)		1.50
Expired (in dollars per share)		1.73
Forfeited (in dollars per share)		0.63
Ending balance (in dollars per share)		1.77
Vested at end of period (in dollars per share)		1.47
Expected to vest at end of period (in dollars per share)		$ 2.13
Weighted Average Remaining Contractual Life (Years)
Outstanding	0 years	8 years 5 months 23 days
Vested at end of period (in years)		7 years 11 months 8 days
Expected to vest at end of period (in years)		9 years 1 month 9 days
Aggregate Intrinsic Value
Outstanding at beginning period	$ 0	$ 0
Exercised		5,588,929	$ 59,965
Outstanding at end of period		10,518,390
Vested at end of period		8,010,123
Expected to vest at end of period		$ 2,508,267