Income Taxes (Income Tax Rate Reconciliation) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2014
Income Tax Disclosure [Abstract]
U.S. federal income tax rate	35.00%		35.00%	35.00%
Income Tax Expense (Benefit), Continuing Operations, Income Tax Reconciliation [Abstract]
United States federal tax expense (benefit) at statutory rate	$ (4,785)	$ (7,067)	$ (12,949)
State taxes, net of United States federal tax expense (benefit)	(694)	(273)	(533)
Change in valuation allowance	5,804	1,133	13,148
Non-deductible stock compensation	448	587	144
Impact of non-U.S. jurisdictional tax rate difference	(117)	603	335
Research and development tax credit	(12)	0	(338)
Increase (reversal) of unrecognized tax benefits	0	0	135
Basis difference in investment	159	1,397	538
Non-U.S. withholding tax	470	435	452
Change in indefinite reinvestment assertion	998	0	0
Other	(69)	407	(156)
Total income tax expense (benefit)	$ 2,202	$ (2,778)	$ 776