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Investment Securities (Narrative) (Details) | 3 Months Ended |
--- | --- | ---
Dec. 31, 2019 USD ($) security | Dec. 31, 2020 USD ($)
Schedule of Investments [Line Items] |  |
Available-for-sale Securities Pledged as Collateral | $ 147,283,000 | $ 102,959,000
Debt Securities, Available-for-sale, Restriction Type [Extensible List] | us-gaap:CollateralPledgedMember | us-gaap:CollateralPledgedMember
FHLB [Member] |  |
Schedule of Investments [Line Items] |  |
Letter of credit outstanding, amount | $ 169,051,000 | $ 288,950,000
ASU 2019-04 [Member] |  |
Schedule of Investments [Line Items] |  |
Debt securities, held-to-maturity with an aggregate amortized cost | 67,096,000 |
Gain (loss) on sale of debt securities | $ 1,779,000 |
Number of held-to-maturity debt securities | security | 113 |
Number of held-to-maturity debt securities sold | security | 113 |

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