Acquisition of Bellwether Bio - Narrative (Details) - USD ($) $ in Thousands	1 Months Ended	9 Months Ended
	Apr. 30, 2019	Sep. 30, 2019	Sep. 30, 2018
Business Acquisition [Line Items]
Contingent liability from business acquisition		$ 1,065	$ 0
Acquisition related costs		422
Bellweather Bio, Inc.
Business Acquisition [Line Items]
Total purchase consideration	$ 8,700
Cash paid upon closing	7,600
Contingent liability from business acquisition	1,100
Identified intangible assets	6,700
Commercialization Milestones | Bellweather Bio, Inc.
Business Acquisition [Line Items]
Maximum contingent liability	10,000
Earn-Out Consideration | Bellweather Bio, Inc.
Business Acquisition [Line Items]
Maximum contingent liability	10,000
Fair Value, Measurements, Recurring
Business Acquisition [Line Items]
Contingent liability from business acquisition		0
Fair Value, Measurements, Recurring | Level 2
Business Acquisition [Line Items]
Contingent liability from business acquisition		$ 1,065
Covenants Not To Compete | Bellweather Bio, Inc.
Business Acquisition [Line Items]
Identified intangible assets	$ 2,500
Estimated useful life	6 years