Licensed Technology (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Licensing and milestone fees		$ 1.6	$ 0.5	$ 0.8
Scenario, Forecast [Member] | GeorgeWashington [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Licensing and milestone fees	$ 0.5
Scenario, Forecast [Member] | Inserm [Member] [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Licensing and milestone fees	$ 4.1