Income Taxes - Income Tax Expense/(Benefit) Related to Continuing Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
U.S. Federal:
Current	$ 0	$ 0
Deferred	0	0
U.S. State:
Current	0	0
Deferred	0	0
Income tax expense (benefit)	$ 0	$ 0