Property, Plant, and Equipment, Net (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Property, Plant and Equipment [Line Items]
Construction in progress	$ 111,910	$ 88,909
Depreciation expense	55,140	41,550	$ 45,994
Service Life [Member]
Property, Plant and Equipment [Line Items]
Depreciation expense		(12,000)
Second Campus Rockford Illinois [Member]
Property, Plant and Equipment [Line Items]
Construction in progress	49,347	26,741
Office furniture and equipment [Member]
Property, Plant and Equipment [Line Items]
Gross assets acquired on capital leases	1,653	1,653
Accumulated depreciation on capital lease assets	$ 739	$ 322