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Basis of Presentation (Details) $ in Thousands |  | 3 Months Ended |
--- | --- | --- | ---
Jan. 01, 2020 USD ($) | Mar. 31, 2021 USD ($) subsidiary segment | Dec. 31, 2020 USD ($)
Basis of presentation |  |  |
Number of operating segments | segment |  | 1 |
Number of active operating bank subsidiaries | subsidiary |  | 5 |
Retained earnings |  | $ 2,305,584 | $ 2,289,626
ASU 2016-13 | Adjustment |  |  |
Basis of presentation |  |  |
Percentage of allowance for loan losses | 17.20% |  |
Retained earnings | $ 8,300 |  |

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