| **Accumulated Other Comprehensive Income (Loss) - Reclassifications (Loss) (Details) (USD $)In Thousands, unless otherwise specified**                                                                                                                                                                                                                                                                                                   | 3 Months Ended | 12 Months Ended |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------|-----------------|
||
| **Reclassification Adjustments out of Accumulated Other Comprehensive Income [Line Items]**                                                                                                                                                                                                                                                                                                                                              |           |            |   |   |   |   |   |   |   |  |   |  |   |  |
| Interest expense - subordinated debentures and term loans                                                                                                                                                                                                                                                                                                                                                                                |           |            |   |   |   |   |   |   | $ (3,531) |  | $ (5,213) |  | $ (9,892) |  |
| Other expenses - salaries and employee benefits                                                                                                                                                                                                                                                                                                                                                                                          |           |            |   |   |   |   |   |   | (85,413) |  | (79,398) |  | (74,735) |  |
| Income tax expense                                                                                                                                                                                                                                                                                                                                                                                                                       | (3,187)        | (2,667)         | (4,155) | (4,668) | (3,153) | (3,926) | (3,288) | (5,500) | (14,677) |  | (15,867) |  | (8,655) |  |
| NET INCOME                                                                                                                                                                                                                                                                                                                                                                                                                               | 11,447         | 10,403          | 10,815 | 11,865 | 10,310 | 11,236 | 9,205 | 14,371 | 44,530 |  | 45,122 |  | 25,252 |  |
| Amount Reclassified from Accumulated Other Comprehensive Income (Loss) for the Period                                                                                                                                                                                                                                                                                                                                                    |           |            |   |   |   |   |   |   |   |  |   |  |   |  |
| **Reclassification Adjustments out of Accumulated Other Comprehensive Income [Line Items]**                                                                                                                                                                                                                                                                                                                                              |           |            |   |   |   |   |   |   |   |  |   |  |   |  |
| NET INCOME                                                                                                                                                                                                                                                                                                                                                                                                                               |           |            |   |   |   |   |   |   | (1,438) |  | 1,478 |  | 1,749 |  |
| Amount Reclassified from Accumulated Other Comprehensive Income (Loss) for the Period | Unrealized gains (losses) on available for sale securities                                                                                                                                                                                                                                                                                       |           |            |   |   |   |   |   |   |   |  |   |  |   |  |
| **Reclassification Adjustments out of Accumulated Other Comprehensive Income [Line Items]**                                                                                                                                                                                                                                                                                                                                              |           |            |   |   |   |   |   |   |   |  |   |  |   |  |
| Other income - net realized gains on sales of available for sale securities                                                                                                                                                                                                                                                                                                                                                              |           |            |   |   |   |   |   |   | 487 | [1] | 2,389 | [1] | 2,439 | [1] |
| Income tax expense                                                                                                                                                                                                                                                                                                                                                                                                                       |           |            |   |   |   |   |   |   | (170) | [1] | (835) | [1] | (854) | [1] |
| NET INCOME                                                                                                                                                                                                                                                                                                                                                                                                                               |           |            |   |   |   |   |   |   | 317 | [1] | 1,554 | [1] | 1,585 | [1] |
| Amount Reclassified from Accumulated Other Comprehensive Income (Loss) for the Period | Unrealized gains (losses) on cash flow hedges                                                                                                                                                                                                                                                                                                    |           |            |   |   |   |   |   |   |   |  |   |  |   |  |
| **Reclassification Adjustments out of Accumulated Other Comprehensive Income [Line Items]**                                                                                                                                                                                                                                                                                                                                              |           |            |   |   |   |   |   |   |   |  |   |  |   |  |
| Interest expense - subordinated debentures and term loans                                                                                                                                                                                                                                                                                                                                                                                |           |            |   |   |   |   |   |   | (935) | [2] | (217) | [2] |    | [2] |
| Income tax expense                                                                                                                                                                                                                                                                                                                                                                                                                       |           |            |   |   |   |   |   |   | 327 | [2] | 76 | [2] |    | [2] |
| NET INCOME                                                                                                                                                                                                                                                                                                                                                                                                                               |           |            |   |   |   |   |   |   | (608) | [2] | (141) | [2] |    | [2] |
| Amount Reclassified from Accumulated Other Comprehensive Income (Loss) for the Period | Unrealized gains (losses) on defined benefit plans                                                                                                                                                                                                                                                                                               |           |            |   |   |   |   |   |   |   |  |   |  |   |  |
| **Reclassification Adjustments out of Accumulated Other Comprehensive Income [Line Items]**                                                                                                                                                                                                                                                                                                                                              |           |            |   |   |   |   |   |   |   |  |   |  |   |  |
| Other expenses - salaries and employee benefits                                                                                                                                                                                                                                                                                                                                                                                          |           |            |   |   |   |   |   |   | (1,765) |  | 100 |  | 252 |  |
| Income tax expense                                                                                                                                                                                                                                                                                                                                                                                                                       |           |            |   |   |   |   |   |   | 618 |  | (35) |  | (88) |  |
| NET INCOME                                                                                                                                                                                                                                                                                                                                                                                                                               |           |            |   |   |   |   |   |   | $ (1,147) |  | $ 65 |  | $ 164 |  |
|                                                                                                                                                                                                                                                                                                                                                                                                                                          |
| [1]For additional detail related to unrealized gains (losses) on available for sale securities and related amounts reclassified from accumulated other comprehensive income see NOTE 5. INVESTMENT SECURITIES.[2]For additional detail related to unrealized gains (losses) on cash flow hedges and related amounts reclassified from accumulated other comprehensive income see NOTE 13. DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES. |

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| - Definition
This item represents the difference between the gross realized gains and losses realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities. Additionally, this item would include any losses recognized for other than temporary impairments (OTTI) of the subject investments in debt and equity securities.
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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
The aggregate amount of expenditures for salaries, wages, profit sharing and incentive compensation, and other employee benefits, including equity-based compensation, and pension and other postretirement benefit expense.
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|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.
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