Related Party Transactions - Narrative (Details) $ in Thousands	3 Months Ended
	Dec. 31, 2017 USD ($) investment	Dec. 31, 2016 USD ($)
Related Party Transaction [Line Items]
Related party expense	$ 302	$ 288
Related party - general and administrative	81	79
Real Property Management Real Estate Brokerage And Construction Supervision Services | Majestic Property Management Corporation
Related Party Transaction [Line Items]
Related party expense	9	8
Shared Services Agreement | Gould Investors Limited Partnership
Related Party Transaction [Line Items]
Related party - general and administrative	81	79
Affiliated Entity
Related Party Transaction [Line Items]
Related party expense	$ 818	624
Number of investments | investment	2
Affiliated Entity | Payment Of Acquisition Fee
Related Party Transaction [Line Items]
Related party expense	$ 230	$ 300