Property and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Less accumulated depreciation and amortization	$ (625)	$ (429)
Property and equipment, net	1,134	593
Depreciation and amortization	165	233	$ 163
Furniture and equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 403	357
Furniture and equipment | Minimum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	2 years
Furniture and equipment | Maximum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	5 years
Leasehold improvement
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 1,356	$ 665