Financial Commitments & Contingencies and Key License Agreements - Components of Lease Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Commitments and Contingencies Disclosure [Abstract]
Operating lease cost	$ 466	$ 351	$ 1,398	$ 1,202
Variable lease cost	86	108	314	323
Short-term lease cost	17	20	46	59
Total lease cost	$ 569	$ 479	$ 1,758	$ 1,584