Summary of Significant Accounting Policies - Cash and Cash Equivalents (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
License Agreement Term	3 years
Cash and Cash Equivalents
Restricted cash	$ 847	$ 847
Letter of Credit
Cash and Cash Equivalents
Restricted Cash, Asset, Statement of Financial Position [Extensible List]		Other Assets, Noncurrent
Restricted cash		$ 800