Investments in Unconsolidated Entities - Outstanding Borrowings of Unconsolidated Entities and Equity in Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2018	Mar. 31, 2017	Sep. 30, 2017
Schedule of Equity Method Investments [Line Items]
Investments in unconsolidated entities	$ 4,293		$ 4,293		$ 3,994
Equity in income of unconsolidated entities	256	$ 33	155	$ 55
Unconsolidated Entities
Schedule of Equity Method Investments [Line Items]
Investments in unconsolidated entities	4,293		4,293		3,994
Total equity of unconsolidated entities	12,078		12,078		11,811
Total outstanding borrowings of unconsolidated entities	$ 16,474		$ 16,474		$ 15,797