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Loans Receivable - Loan Modifications (Details)	3 Months Ended		9 Months Ended
	Jun. 30, 2019 USD ($) contract	Jun. 30, 2018 USD ($) contract	Jun. 30, 2019 USD ($) contract	Jun. 30, 2018 USD ($) contract
Financing Receivable, Modifications [Line Items]
Number of Contracts | contract	0	0	5	2
Recorded Investment | $	$ 0	$ 0	$ 1,298,000	$ 206,000
Single-family residential
Financing Receivable, Modifications [Line Items]
Number of Contracts | contract			5	2
Recorded Investment | $			$ 1,298,000	$ 206,000

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