Income Taxes Schedule of Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning	$ 12,965	$ 12,830	$ 13,364
Additions based on tax positions related to the current year	938	1,523	1,608
Additions for tax positions of prior years	32	45	228
Settlements			(199)
Reductions for tax positions of prior years	(1,477)	(237)	(302)
Reductions due to lapse of applicable statutes	(899)	(627)	(1,053)
Adjustments due to foreign exchange rate movement	1,008	(569)	(816)
Ending	$ 12,567	$ 12,965	$ 12,830