| **Accumulated Other Comprehensive Income (Loss) - Reclassifications (Loss) (Details) - USD ($) $ in Thousands**                                  | 3 Months Ended | 12 Months Ended |
|--------------------------------------------------------------------------------------------------------------------------------------------------|----------------|-----------------|
||
| **Reclassification Adjustments out of Accumulated Other Comprehensive Income [Line Items]**                                                      |           |            |   |   |   |   |   |   |   |   |   |
| Net realized gains on sales of available for sale securities                                                                                     |           |            |   |   |   |   |   |   | $ 4,269 | $ 2,631 | $ 3,389 |
| Income tax expense                                                                                                                               | $ (5,949)      | $ (8,478)       | $ (7,961) | $ (6,611) | $ (15,210) | $ (7,939) | $ (7,207) | $ (7,168) | (28,999) | (37,524) | (27,609) |
| Subordinated debentures and term loans                                                                                                           |           |            |   |   |   |   |   |   | 8,233 | 7,572 | 7,185 |
| Salaries and employee benefits                                                                                                                   |           |            |   |   |   |   |   |   | 131,704 | 119,812 | 102,552 |
| Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax                                                         |           |            |   |   |   |   |   |   | 3,018 | 1,667 | 2,422 |
| Unrealized gains (losses) on available for sale securities                                                                                       |           |            |   |   |   |   |   |   |   |   |   |
| **Reclassification Adjustments out of Accumulated Other Comprehensive Income [Line Items]**                                                      |           |            |   |   |   |   |   |   |   |   |   |
| Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax                                                         |           |            |   |   |   |   |   |   | 3,373 | 1,710 | 2,203 |
| Unrealized gains (losses) on cash flow hedges                                                                                                    |           |            |   |   |   |   |   |   |   |   |   |
| **Reclassification Adjustments out of Accumulated Other Comprehensive Income [Line Items]**                                                      |           |            |   |   |   |   |   |   |   |   |   |
| Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax                                                         |           |            |   |   |   |   |   |   | (371) | (640) | (813) |
| Unrealized gains (losses) on defined benefit plans                                                                                               |           |            |   |   |   |   |   |   |   |   |   |
| **Reclassification Adjustments out of Accumulated Other Comprehensive Income [Line Items]**                                                      |           |            |   |   |   |   |   |   |   |   |   |
| Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax                                                         |           |            |   |   |   |   |   |   | 16 | 597 |   |
| Amount Reclassified from Accumulated Other Comprehensive Income (Loss) | Unrealized gains (losses) on available for sale securities              |           |            |   |   |   |   |   |   |   |   |   |
| **Reclassification Adjustments out of Accumulated Other Comprehensive Income [Line Items]**                                                      |           |            |   |   |   |   |   |   |   |   |   |
| Net realized gains on sales of available for sale securities                                                                                     |           |            |   |   |   |   |   |   | 4,269 | 2,631 | 3,389 |
| Income tax expense                                                                                                                               |           |            |   |   |   |   |   |   | (896) | (921) | (1,186) |
| Amount Reclassified from Accumulated Other Comprehensive Income (Loss) | Unrealized gains (losses) on cash flow hedges                           |           |            |   |   |   |   |   |   |   |   |   |
| **Reclassification Adjustments out of Accumulated Other Comprehensive Income [Line Items]**                                                      |           |            |   |   |   |   |   |   |   |   |   |
| Income tax expense                                                                                                                               |           |            |   |   |   |   |   |   | 99 | 345 | 437 |
| Amount Reclassified from Accumulated Other Comprehensive Income (Loss) | Unrealized gains (losses) on cash flow hedges | Interest Rate Contracts |           |            |   |   |   |   |   |   |   |   |   |
| **Reclassification Adjustments out of Accumulated Other Comprehensive Income [Line Items]**                                                      |           |            |   |   |   |   |   |   |   |   |   |
| Subordinated debentures and term loans                                                                                                           |           |            |   |   |   |   |   |   | (470) | (985) | (1,250) |
| Amount Reclassified from Accumulated Other Comprehensive Income (Loss) | Unrealized gains (losses) on defined benefit plans                      |           |            |   |   |   |   |   |   |   |   |   |
| **Reclassification Adjustments out of Accumulated Other Comprehensive Income [Line Items]**                                                      |           |            |   |   |   |   |   |   |   |   |   |
| Income tax expense                                                                                                                               |           |            |   |   |   |   |   |   | (4) | (209) | (556) |
| Salaries and employee benefits                                                                                                                   |           |            |   |   |   |   |   |   | 20 | 806 | 1,588 |
| Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax                                                         |           |            |   |   |   |   |   |   | $ 16 | $ 597 | $ 1,032 |

| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of realized gain (loss) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).
+ References
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|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.
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|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of the cost of borrowed funds accounted for as interest expense for debt.
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|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of expense for salary, wage, profit sharing; incentive and equity-based compensation; and other employee benefit.
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| - 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.
+ References
No definition available.
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|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount after tax of reclassification adjustments of other comprehensive income (loss).
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