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Comprehensive Income (Components of Accumulated Other Comprehensive Income) (Details) (USD $) In Thousands, unless otherwise specified | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2012 | Sep. 30, 2011 | Sep. 30, 2012 | Sep. 30, 2011
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract] |  |  |  |
Beginning balance, OTTI Related Net Unrealized Loss |  |  | $ (3,500) |
Beginning balance, HTM related Net Unrealized Gain |  |  | 4,622 |
Beginning balance, All Other Net Unrealized Gain |  |  | 96,125 |
Beginning balance, Defined Benefit Pension and Post-retirement Plans |  |  | (54,953) |
Beginning balance, Total Accumulated OCI |  |  | 42,294 |
Non-credit portion of other-than-temporary impairments recognized in other comprehensive income | (1,320) | 53 | (1,633) | (336)
Changes in HTM Related Net Unrealized Gain |  |  | (1,249) |
Unrealized holding gains during the period |  |  | 39,548 |
Changes in Defined Benefit Pension and Post-retirement Plans | 928 | 702 | 2,785 | 2,187
Other comprehensive income |  |  | 42,717 |
Ending balance, OTTI Related Net Unrealized Loss | (1,867) |  | (1,867) |
Ending balance, HTM related Net Unrealized Gain | 3,373 |  | 3,373 |
Ending balance, All Other Net Unrealized Gain | 135,673 |  | 135,673 |
Ending balance, Defined Benefit Pension and Post-retirement Plans | (52,168) |  | (52,168) |
Ending balance, Total Accumulated OCI | $ 85,011 |  | $ 85,011 |

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