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Loans and Allowance for Credit Losses - Collateral dependent loans and related ACL (Details) - USD ($) $ in Thousands | Dec. 31, 2021 | Sep. 30, 2021 | Jun. 30, 2021 | Dec. 31, 2020 | Sep. 30, 2020 | Jun. 30, 2020
--- | --- | --- | --- | --- | --- | ---
Related allowance for credit losses | $ 32,529 | $ 32,543 | $ 33,222 | $ 35,471 | $ 35,084 | $ 25,139
Collateral-dependent Loans | 1- to 4-family residential loans |  |  |  |  |  |
Amortized cost | 880 |  | 895 |  |  |
Related allowance for credit losses | 208 |  | 223 |  |  |
Residential Real Estate |  |  |  |  |  |
Related allowance for credit losses | 10,757 | $ 10,634 | 11,192 | $ 10,398 | $ 8,629 | $ 4,875
Residential Real Estate | Collateral-dependent Loans |  |  |  |  |  |
Amortized cost | 880 |  | 895 |  |  |
Related allowance for credit losses | $ 208 |  | $ 223 |  |  |

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