Income Taxes (Schedule of Components of Income Tax Expense) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current tax:
Federal									$ (81)	$ (219)	$ (535)
State									146	(95)	401
Foreign									978	1,189	1,238
Current Income Tax Expense (Benefit)									1,043	875	1,104
Deferred taxes:
Federal									(5,417)	(12,500)	(42,113)
State									143	902	29
Foreign									28	(9)	3,401
Deferred Income Tax Expense (Benefit)									(5,246)	(11,607)	(38,683)
Income tax benefit	$ 5,403	$ (17)	$ (1,135)	$ (48)	$ 5,086	$ 1,698	$ 1,990	$ 1,958	$ 4,203	$ 10,732	$ 37,579