Accounts Payable and Accrued Liabilities - Summary (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Payables and Accruals [Abstract]
Accounts payable	$ 16,367	$ 8,531
Accrued clinical expense	21,290	10,154
Accrued development and other expense	2,510	1,243
Accrued compensation and benefits	7,915	5,847
Total accounts payable and accrued liabilities	$ 48,082	25,775
Noncurrent deferred revenue		$ 100