Property, Plant, and Equipment, Net (Property, Plant, and Equipment - Net) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016	Sep. 30, 2016
Property, Plant, and Equipment, Net
Land and Land Improvements	$ 87,514		$ 87,514		$ 87,696
Buildings and improvements	526,597		526,597		527,704
Leasehold improvements	14,990		14,990		15,213
Machinery and production equipment	488,851		488,851		484,315
Computer equipment and software	122,570		122,570		117,984
Office furniture and equipment	26,841		26,841		29,344
Other	19,165		19,165		18,969
Construction in progress	108,020		108,020		88,909
Property, Plant and Equipment, Gross, Total	1,394,548		1,394,548		1,370,134
Less accumulated depreciation	(506,313)		(506,313)		(493,784)
Property, Plant and Equipment, Net, Total	888,235		888,235		$ 876,350
Depreciation expense	13,663	$ 8,633	26,118	$ 18,749
Capitalized interest	$ 481	$ 2,267	$ 953	$ 4,140