Property, Plant, and Equipment, Net (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Construction in progress	$ 223,958	$ 252,763	$ 223,958
Property, Plant and Equipment, Net	513,279	756,100	513,279
Asset Impairment Charges	3,138	0	3,138	$ 0
Second Campus Rockford Illinois [Member]
Construction in progress	85,283	47,629	85,283
Capitalized interest	2,963	499	2,963
New Campus Fort Collins Colorado [Member]
Construction in progress	37,268	151,669	37,268
Capitalized interest	2,392	5,205	2,392
Building Site Niles Illinois [Member]
Construction in progress	55,629	0	55,629
Disposal Group, Held-for-sale, Not Discontinued Operations [Member]
Property, Plant and Equipment, Net	$ 2,465	681	$ 2,465
Building and Building Improvements [Member] \| Second Campus Rockford Illinois [Member]
Contruction in progress placed into service		120,000
Buildings and improvements and Office furniture and equipment [Member] \| Building Site Niles Illinois [Member]
Contruction in progress placed into service		$ 77,000

Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

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Amount of structure or a modification to a structure under construction. Includes recently completed structures or modifications to structures that have not been placed into service.

+ References

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-Publisher FASB

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Amount after accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business to produce goods and services and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

+ References

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-SubTopic 10

-Section S99

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-Publisher SEC

-Name Regulation S-X (SX)

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Amount of reclassification, impairment, donation, or other change to long-lived, physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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The amount of interest that was capitalized on capital projects that have not been completed and assets being constructed that are not ready to be placed into service.

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