Summary of Significant Accounting Policies Accrued Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Accrued Liabilities [Line Items]
Accrued research and development services current	$ 50,217	$ 29,033
Accrued compensation and benefits current	6,023	9,644
Operating Lease, Liability, Current	553	553
Other Accrued Liabilities, Current	1,704	2,921
Accrued Liabilities	$ 58,497	$ 42,151