Significant Accounting Policies - Additional Information (Details)	12 Months Ended
	Dec. 31, 2017 USD ($) Segment	Dec. 31, 2016 USD ($)
Schedule Of Significant Accounting Policies [Line Items]
Property, plant and equipment, net | $	$ 173,000	$ 0
Number of operating segment	1
Number of Reportable Segments	1
Minimum
Schedule Of Significant Accounting Policies [Line Items]
Effective income tax rate	50.00%
Leasehold Improvements
Schedule Of Significant Accounting Policies [Line Items]
Estimated useful life	5 years
Software | Minimum
Schedule Of Significant Accounting Policies [Line Items]
Estimated useful life	3 years
Software | Maximum
Schedule Of Significant Accounting Policies [Line Items]
Estimated useful life	5 years