Schedule II - Valuation and Qualifying Accounts (Details 1) - Valuation Allowance of Deferred Tax Assets [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Movement in Valuation Allowances and Reserves [Roll Forward]
Allowance, Beginning Balance	$ 14,957	$ 14,401	$ 15,856
Additions charged to income tax expense	1,161	759	1,043
Additions (reductions) charged to other comprehensive income	(123)	(17)	(59)
Reductions credited to income tax expense	(6,773)	(5,638)	(1,216)
Changes due to foreign currency translation	1,001	(133)	(2,204)
Acquisition		5,585	(981)
Allowance, Ending Balance	$ 10,223	$ 14,957	$ 14,401