Income Tax Expense (Components of Net Loss and Income Tax (Benefit) Expense) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest [Abstract]
United States	$ (56,178)	$ (135,925)	$ (44,114)
Foreign	(10,681)	(18,254)	(15,647)
Net loss before income tax	(66,859)	(154,179)	(59,761)
Current:
Federal	(102)	(50)	50
State	102	90	100
Foreign	237	458	148
Total current	237	498	298
Deferred:
Federal	(699)	0	(8,621)
State	0	0	(1,008)
Foreign	3	0	(6)
Total deferred	(696)	0	(9,635)
Total:
Federal	(801)	(50)	(8,571)
State	102	90	(908)
Foreign	240	458	142
Income tax expense (benefit)	$ (459)	$ 498	$ (9,337)