Loans Receivable - Loan Modifications (Details) $ in Thousands	3 Months Ended	9 Months Ended
Jun. 30, 2016 USD ($) contract	Jun. 30, 2015 USD ($) contract	Jun. 30, 2016 USD ($) contract	Jun. 30, 2015 USD ($) contract
Financing Receivable, Modifications [Line Items]
Number of contracts (in contracts) \| contract	7	11	21	26
Recorded investment \| $	$ 2,227	$ 1,895	$ 4,211	$ 4,320
Single-family residential
Financing Receivable, Modifications [Line Items]
Number of contracts (in contracts) \| contract	3	9	14	19
Recorded investment \| $	$ 1,570	$ 1,594	$ 3,108	$ 3,329
Construction
Financing Receivable, Modifications [Line Items]
Number of contracts (in contracts) \| contract	1	0	1	0
Recorded investment \| $	$ 279	$ 0	$ 279	$ 0
Land - consumer lot loans
Financing Receivable, Modifications [Line Items]
Number of contracts (in contracts) \| contract	2	2	4	7
Recorded investment \| $	$ 204	$ 301	$ 498	$ 991
Commercial real estate
Financing Receivable, Modifications [Line Items]
Number of contracts (in contracts) \| contract	1	0	2	0
Recorded investment \| $	$ 174	$ 0	$ 326	$ 0