| **Acquisitions and Divestitures - Pro Forma Information (Details) - USD ($) $ / shares in Units, $ in Thousands** | 12 Months Ended |
|-------------------------------------------------------------------------------------------------------------------|-----------------|
||
| **Business Combinations [Abstract]**                                                                              |            |   |
| Total revenue (net interest income plus other income)                                                             | $ 291,614       | $ 284,890 |
| Net income                                                                                                        | 60,497          | 64,174 |
| Net income available to common shareholders                                                                       | $ 60,497        | $ 64,174 |
| **Earnings per share:**                                                                                           |            |   |
| Basic (in dollars per share)                                                                                      | $ 1.49          | $ 1.58 |
| Diluted (in dollars per share)                                                                                    | $ 1.48          | $ 1.57 |

| X                                                                                                                                                                                                                                                                                                                           |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Business Acquisition, Pro Forma Net Income Loss, Attributable to Parent
+ References
No definition available.
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| X                                                                                                                                                                                                                                                                                                                                        |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Business Acquisition, Pro Forma Revenue, Net Interest Income Plus Other Income
+ References
No definition available.
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The pro forma basic net income per share for a period as if the business combination or combinations had been completed at the beginning of a period.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(2)-(3) -URI http://asc.fasb.org/extlink&oid=65885119&loc=d3e1392-128463
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The pro forma diluted net income per share for a period as if the business combination or combinations had been completed at the beginning of a period.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(2)-(3) -URI http://asc.fasb.org/extlink&oid=65885119&loc=d3e1392-128463
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| X                                                                                                                                                                                                                        |
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| - References
No definition available.
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The pro forma net Income or Loss for the period as if the business combination or combinations had been completed at the beginning of a period.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(2)-(3) -URI http://asc.fasb.org/extlink&oid=65885119&loc=d3e1392-128463
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| X                                                                                                                                                                                                      |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - References
No definition available.
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