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Loans Receivable - Additional Information (Details) - USD ($) $ in Thousands | 3 Months Ended |
--- | --- | ---
Dec. 31, 2018 | Dec. 31, 2017 | Sep. 30, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Nonaccrual interest income recognized | $ 843 |  |
Impaired, interest lost on nonaccrual loans | $ 587 |  |
Ratio of past due loans to total loans, net of charge-offs and LIPs | 0.42% |  | 0.42%
Percent of TDRs classified as performing | 96.00% |  |
Troubled debt restructuring, amount | $ 283 | $ 9,268 |
Basis point reduction, minimum | 1.00% |  |
Basis point reduction, maximum | 2.00% |  |
Single family residential loans as percentage of restructured loans | 89.40% |  |
Minimum |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Term for payment and rate reduction | 6 months |  |
Maximum |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Term for payment and rate reduction | 24 months |  |
Performing Loans |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Troubled debt restructuring, amount | $ 149,693 |  |

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