Income Taxes - Schedule of Income Tax Expense (Benefit) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Tax benefit computed at federal statutory rate	$ (3,084)	$ (2,216)
State taxes, net of federal benefit	557	(156)
(Decrease) increase in valuation allowance	(10,645)	2,048
State NOL expiration/write-off	0	321
Adjustment to income tax accruals	(870)	5
State research credit expiration	0	3
Non-deductible expenses	317	3
Impact of Tax Reform	13,736	0
Total income tax expense	$ 11	$ 8