Property, Plant, and Equipment (Property, Plant, and Equipment, Net) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Sep. 30, 2018
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, gross	$ 1,641,706	$ 1,624,874
Less accumulated depreciation	(581,150)	(564,869)
Property, plant, and equipment, net	1,060,556	1,060,005
Land and Land Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, gross	93,958	94,146
Building and Building Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, gross	566,562	565,065
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, gross	17,897	17,954
Machinery and Production Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, gross	677,086	668,986
Computer Equipment and Software [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, gross	125,272	124,788
Office furniture and equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, gross	32,210	31,533
Other [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, gross	19,396	19,366
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, gross	$ 109,325	$ 103,036