Property and Equipment, Net (Schedule of Property and Equipment, Net) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Property and Equipment [Line Items]
Property and equipment	$ 1,570,200	$ 1,455,600
Less accumulated depreciation and amortization	(833,800)	(749,100)
Property and equipment, net	736,447	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	29,600	26,700
Machinery and Equipment [Member]
Property and Equipment [Line Items]
Property and equipment	1,350,600	1,261,900
Office Furniture and Equipment [Member]
Property and Equipment [Line Items]
Property and equipment	160,300	149,900
Construction in Progress [Member]
Property and Equipment [Line Items]
Property and equipment	$ 25,100	$ 12,500