Income Taxes (Components of Income Tax Expense) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current Income Tax Expense (Benefit) [Abstract]
Federal	$ 2,390	$ 1,259	$ 1,267
State	1,153	310	191
Foreign	8,266	3,266	4,789
Current income tax provision	11,809	4,835	6,247
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Federal	(5,558)	78	808
State	(976)	295	720
Foreign	(4,498)	(3,571)	(669)
Deferred income tax provision	(11,032)	(3,198)	859
Total provision for income taxes	$ 777	$ 1,637	$ 7,106