| **Loans and Allowance - Narrative (Details) - USD ($)**                        | 3 Months Ended | 6 Months Ended |               |              |               |              |
|--------------------------------------------------------------------------------|----------------|----------------|---------------|--------------|---------------|--------------|
||
| **Receivables [Abstract]**                                                     |           |           |          |         |          |         |   |
| Loans held for sale                                                            | $ 5,854,000    |           | $ 5,854,000   |         | $ 4,778,000   |         |   |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**               |           |           |          |         |          |         |   |
| Loans                                                                          | 7,511,370,000  |           | 7,511,370,000 |         | 7,224,467,000 |         |   |
| Loans - allowance for loan losses                                              | 81,274,000     | $ 77,543,000   | 81,274,000    | $ 80,902,000 | 80,552,000    | $ 76,420,000 | $ 75,032,000 |
| Residential                                                                    |           |           |          |         |          |         |   |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**               |           |           |          |         |          |         |   |
| Loans                                                                          | 1,541,808,000  |           | 1,541,808,000 |         | 1,494,578,000 |         |   |
| Loans - allowance for loan losses                                              | $ 14,471,000   | $ 14,424,000   | $ 14,471,000  | $ 14,373,000 | 14,322,000    | $ 14,049,000 | $ 13,537,000 |
| Percentage of troubled debt restructured loans                                 | 100.00%        | 100.00%        | 100.00%       |         |          |         |   |
| Mortgage loans with formal foreclosure proceedings                             | $ 777,000      |           | $ 777,000     |         | 800,000       |         |   |
| Loans acquired with deteriorated credit quality                                |           |           |          |         |          |         |   |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**               |           |           |          |         |          |         |   |
| Loans                                                                          | 14,083,000     |           | 14,083,000    |         | 15,784,000    |         |   |
| Loans acquired with deteriorated credit quality | Commercial and consumer loan |           |           |          |         |          |         |   |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**               |           |           |          |         |          |         |   |
| Loans                                                                          | 1,824,000      |           | 1,824,000     |         | 1,541,000     |         |   |
| Loans - allowance for loan losses                                              | 329,000        |           | 329,000       |         | 0             |         |   |
| Loans acquired with deteriorated credit quality | Residential                  |           |           |          |         |          |         |   |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**               |           |           |          |         |          |         |   |
| Loans                                                                          | $ 825,000      |           | $ 825,000     |         | $ 1,293,000   |         |   |

| X                                                                                                                                                                                                                                                                                                                                                                                                |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Financing Receivable, Modifications, Post-Modification, Loans as Percentage of Troubled Debt Restructured Loans
+ References
No definition available.
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| X                                                                                                                                                                                                                                         |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Loans and Leases Receivable
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.
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No definition available.
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|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.
+ References
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The face amount of loans that will be sold to other entities.
+ References
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Recorded investment of consumer mortgage loan receivables secured by residential real estate properties for which formal foreclosure proceedings are in process.
+ References
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| - References
No definition available.
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