Acquisition - Intangible Assets Acquired (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended	12 Months Ended
	Apr. 30, 2019	Mar. 31, 2020	Dec. 31, 2019
Acquired license
Acquired Finite-Lived Intangible Assets [Line Items]
Remaining Weighted Average Useful Life		10 years 7 months 6 days	9 years 6 months
Bellweather Bio, Inc.
Acquired Finite-Lived Intangible Assets [Line Items]
Identified intangible assets	$ 6,700
Bellweather Bio, Inc. | Acquired license
Acquired Finite-Lived Intangible Assets [Line Items]
Identified intangible assets	$ 5,100
Remaining Weighted Average Useful Life	10 years
Bellweather Bio, Inc. | IPR&D
Acquired Finite-Lived Intangible Assets [Line Items]
Identified intangible assets	$ 1,600