Property and Equipment, Net (Schedule of Property and Equipment, Net) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Property and Equipment [Line Items]
Property and equipment	$ 1,489,000	$ 1,455,600
Less accumulated depreciation and amortization	(779,200)	(749,100)
Property and equipment, net	709,806	706,506
Land [Member]
Property and Equipment [Line Items]
Property and equipment	4,600	4,600
Building and Leasehold Improvements [Member]
Property and Equipment [Line Items]
Property and equipment	26,600	26,700
Machinery and Equipment [Member]
Property and Equipment [Line Items]
Property and equipment	1,285,800	1,261,900
Office Furniture and Equipment [Member]
Property and Equipment [Line Items]
Property and equipment	156,900	149,900
Construction in Progress [Member]
Property and Equipment [Line Items]
Property and equipment	$ 15,100	$ 12,500