Intangible Assets Narrative (Details) $ in Thousands, € in Millions	1 Months Ended		12 Months Ended
	Apr. 30, 2017 USD ($)	Apr. 30, 2017 EUR (€)	Dec. 31, 2019 USD ($)	Dec. 31, 2019 EUR (€)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Finite-Lived Intangible Assets [Line Items]
Payment of milestone related to intangible assets			$ 0		$ 0	$ 8,712
Future amortization expense					$ 800	$ 500
Future amortization expense, estimated useful life			8 years 3 months	8 years 3 months
Collaborative Arrangement | Ipsen
Finite-Lived Intangible Assets [Line Items]
Payment of milestone related to intangible assets	$ 8,700	€ 8.0	$ 8,700	€ 8.0