Investments in Unconsolidated Entities and Marketable Securities - Narrative (Details) - USD ($)	1 Months Ended	12 Months Ended
	Mar. 31, 2015	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Schedule of Equity Method Investments [Line Items]
Loss on sale of investments	$ 1,800,000
Fair value changes			$ 500,000
South Edge
Schedule of Equity Method Investments [Line Items]
Amount paid for infrastructure and development costs		$ 4,500,000	3,300,000	$ 1,000,000
Remaining obligation		700,000
Financial Guarantee
Schedule of Equity Method Investments [Line Items]
Impairment of unconsolidated entity investment		$ 0	$ 0