|**Commitments and Contingent Liabilities (Tables)**                 | 3 Months Ended                                                                                                                                                                                                                                                                                                                                                                       
|------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
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|**Commitments and Contingencies Disclosure [Abstract]**             |                                                                                                                                                                                                                                                                                                                                                                                      
|Notional Amount of Outstanding Commitments                          | The following table identifies the notional amount of those instruments at:March 31, 2022December 31, 2021(dollars in thousands)Financial instruments whose contract amounts represent credit risk:Commitments to extend credit$2,376,865$2,353,991Financial standby letters of credit17,98518,824Performance standby letters of credit17,58410,663Commercial letters of credit975975
|                                                                    |                                                                                                                                                                                                                                                                                                                                                                                      
|                                                                    | March 31, 2022                                                                                                                                                                                                                                                                                                                                                                       
|                                                                    | (dollars in thousands)                                                                                                                                                                                                                                                                                                                                                               
|Financial instruments whose contract amounts represent credit risk: |                                                                                                                                                                                                                                                                                                                                                                                      
|Commitments to extend credit                                        | $                                                                                                                                                                                                                                                                                                                                                                                    
|Financial standby letters of credit                                 | 17,985                                                                                                                                                                                                                                                                                                                                                                               
|Performance standby letters of credit                               | 17,584                                                                                                                                                                                                                                                                                                                                                                               
|Commercial letters of credit                                        | 975                                                                                                                                                                                                                                                                                                                                                                                  

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