Property and Equipment, net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Property, equipment and leasehold improvements, at cost	$ 7,534	$ 7,320
Less accumulated depreciation	(5,949)	(4,400)
Property, equipment and leasehold improvements, net	1,585	2,920
Depreciation expense	1,728	2,050
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property, equipment and leasehold improvements, at cost	1,730	1,686
Office furniture and equipment
Property, Plant and Equipment [Line Items]
Property, equipment and leasehold improvements, at cost	1,731	1,743
Computer and office equipment
Property, Plant and Equipment [Line Items]
Property, equipment and leasehold improvements, at cost	4,073	3,768
Construction in progress
Property, Plant and Equipment [Line Items]
Property, equipment and leasehold improvements, at cost	$ 0	$ 123