Accrued Expenses and Other Liabilities - Schedule of Accrued Expenses and Other Liabilities (Detail) - USD ($)	Mar. 31, 2020	Dec. 31, 2019
Payables and Accruals [Abstract]
Accrued preclinical and clinical trial expenses	$ 940,963	$ 1,183,513
Accrued professional fees	3,309,351	1,241,526
Accrued compensation and benefits	1,814,396	3,064,645
Accrued license fees	3,945,991	8,751,991
Accrued purchases	1,243,991	1,313,310
Accrued contributions	1,135,000	1,535,000
Operating lease liability	306,677	300,518
Accrued variable consideration	1,308,344	884,764
Income tax payable	2,143,490	1,533,696
Other	139,733	172,332
Current accrued expenses and other liabilities	16,287,936	19,981,295
Lease liability - non-current	568,421	647,532
Non-current accrued expenses and other liabilities	568,421	647,532
Total accrued expenses and other liabilities	$ 16,856,357	$ 20,628,827