Related-Party Transactions - Deferred Revenue (Details) - Janssen Pharmaceuticals Inc [Member] - Collaboration Agreement [Member] - USD ($)		3 Months Ended		6 Months Ended		12 Months Ended
	Jan. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Related Party Transaction [Line Items]
Non-refundable upfront fee from Janssen	$ 100,000,000				$ 100,000,000.0
Deferred revenue recognized as license revenue during period		$ (2,473,705)	$ (1,981,676)	$ (6,683,281)	$ (2,766,636)	$ (13,291,956)
Effects of exchange rate				(5,836,157)		(493,953)
Deferred revenue		$ 73,694,653		$ 73,694,653		$ 86,214,091