Fixed Assets (Schedule of Fixed Assets) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Fixed assets, at cost	$ 424,056	$ 337,362
Less accumulated depreciation and amortization	195,106	164,614
Fixed assets, net	228,950	172,748
Land
Property, Plant and Equipment [Line Items]
Fixed assets, at cost	19,176	13,802
Buildings and Improvements
Property, Plant and Equipment [Line Items]
Fixed assets, at cost	118,555	106,831
Leasehold Improvements
Property, Plant and Equipment [Line Items]
Fixed assets, at cost	12,707	11,918
Machinery and Equipment
Property, Plant and Equipment [Line Items]
Fixed assets, at cost	201,081	167,691
Furniture and Fixtures
Property, Plant and Equipment [Line Items]
Fixed assets, at cost	39,047	27,053
Construction in Progress
Property, Plant and Equipment [Line Items]
Fixed assets, at cost	$ 33,490	$ 10,067
Minimum | Buildings and Improvements
Property, Plant and Equipment [Line Items]
Estimated useful life in years	10 years
Minimum | Leasehold Improvements
Property, Plant and Equipment [Line Items]
Estimated useful life in years	3 years
Minimum | Machinery and Equipment
Property, Plant and Equipment [Line Items]
Estimated useful life in years	3 years
Minimum | Furniture and Fixtures
Property, Plant and Equipment [Line Items]
Estimated useful life in years	3 years
Maximum | Buildings and Improvements
Property, Plant and Equipment [Line Items]
Estimated useful life in years	40 years
Maximum | Leasehold Improvements
Property, Plant and Equipment [Line Items]
Estimated useful life in years	10 years
Maximum | Machinery and Equipment
Property, Plant and Equipment [Line Items]
Estimated useful life in years	15 years
Maximum | Furniture and Fixtures
Property, Plant and Equipment [Line Items]
Estimated useful life in years	8 years