Acquisition Purchase Price Allocation (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Apr. 24, 2017	Dec. 31, 2016	Dec. 31, 2015
Business Acquisition [Line Items]
Other Current Assets		$ 726
Property, Plant and Equipment		2,447
Identifiable Intangible Assets		8,820
Net Assets Acquired		11,993
Goodwill	$ 359,688	8,007	$ 345,269	$ 342,111
Total Purchase Price		$ 20,000