Share-Based Compensation - Summary of Stock Option Activity (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Aggregated Intrinsic Value
Exercised	$ 2,400,000	$ 0
Options
Options Outstanding
Outstanding at January 1, 2020	14,936,726
Granted	15,854,166
Exercised	(2,421,657)
Expired	(1,682,658)
Forfeited	(1,599,161)
Outstanding at December 31, 2020	25,087,416	14,936,726
Vested as of December 31, 2020 (in shares)	15,219,708
Expected to vest as of December 31, 2020 (in shares)	9,867,708
Weighted Average Exercise Price
Outstanding at January 1, 2020	$ 2.13
Granted	0.60
Exercised	0.78
Expired	2.72
Forfeited	1.58
Outstanding at December 31, 2020	1.29	$ 2.13
Vested as of December 31, 2020 (in dollars per share)	1.64
Expected to vest as of December 31, 2020 (in dollars per share)	$ 0.75
Weighted Average Remaining Contractual Life (Years)
Outstanding at January 1, 2020	7 years 11 months 1 day
Outstanding at December 31, 2020	7 years 11 months 1 day
Vested at the end (in years)	6 years 11 months 26 days
Expected to vest at the end (in years)	9 years 4 months 9 days
Aggregated Intrinsic Value
Outstanding at December 31, 2020	$ 18,554,241
Vested as of December 31, 2020	6,331,116
Expected to vest as of December 31, 2020	$ 12,223,125