Accounts Payable and Accrued Liabilities - Summary (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Payables and Accruals [Abstract]
Accounts payable	$ 18,117	$ 16,367
Accrued clinical expense	32,240	21,290
Accrued development and other expense	7,151	2,510
Accrued compensation and benefits	13,964	7,915
Total accounts payable and accrued liabilities	$ 71,472	$ 48,082