Income Taxes (Details) - USD ($)
$ in Thousands
3 Months Ended 9 Months Ended
Sep. 30, 2017
Sep. 30, 2016
Sep. 30, 2017
Sep. 30, 2016
Income Taxes.        
Current Federal, State and Local, Tax Expense (Benefit) $ 0 $ 0 $ 0 $ 0
Foreign income tax (benefit) expense $ (12) $ 27 $ (12) $ 27