Debt Obligations - Schedule of Debt Obligations (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Sep. 30, 2017
Debt Obligations
Deferred mortgage costs	$ (7,040)	$ (6,727)
Total debt obligations, net of deferred costs	820,565	734,844
Mortgages payable
Debt Obligations
Total debt obligations, net of deferred costs	790,205	704,171
Deferred mortgage costs	(6,673)	(6,345)
Junior subordinated notes
Debt Obligations
Total debt obligations, net of deferred costs	37,400	37,400
Deferred mortgage costs	$ (367)	$ (382)