Related Party Transactions - Narrative (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2018 USD ($) property	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($) property	Jun. 30, 2017 USD ($)
Related Party Transaction [Line Items]
Related party expense	$ 317	$ 302	$ 936	$ 891
Related party - general and administrative	160	84	389	266
Real Property Management Real Estate Brokerage And Construction Supervision Services | Majestic Property Management Corporation
Related Party Transaction [Line Items]
Related party expense	6	9	25	25
Shared Services Agreement | Gould Investors Limited Partnership
Related Party Transaction [Line Items]
Related party - general and administrative	160	84	388	266
Affiliated Entity
Related Party Transaction [Line Items]
Related party expense	$ 926	726	$ 2,693	2,022
Number of investments | property	2		2
Affiliated Entity | Payment of Acquisition Fee
Related Party Transaction [Line Items]
Related party expense	$ 513	$ 1,255	$ 2,043	$ 1,904