Property and Equipment, net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Less - accumulated depreciation	$ (1,014)	$ (13,155)
Property and equipment, net	544	1,911
Depreciation	459	811	$ 1,224
Laboratory equipment
Property, Plant and Equipment [Line Items]
Total property and equipment	0	8,864
Software, office and computer equipment
Property, Plant and Equipment [Line Items]
Total property and equipment	1,258	2,487
Furniture, fixtures and fittings
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 300	$ 3,715