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Comprehensive Income (Components of Accumulated Other Comprehensive Income) (Details) - USD ($) | 3 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2015 | Sep. 30, 2015 | Jun. 30, 2015 | Mar. 31, 2015 | Dec. 31, 2014 | Sep. 30, 2014 | Jun. 30, 2014 | Mar. 31, 2014 | Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |  |  |  |  |  |  |  |  |  |
Balance December, |  |  |  | $ 19,788,000 |  |  |  |  | $ 19,788,000 |  |
Other Comprehensive Income Loss Reclassification Adjustment From AOCI For Non Credit Other Than Temporary Impaired Securities Net Of Tax |  |  |  |  |  |  |  |  | (232,000) | $ (1,085,000) | $ (9,000)
Amount reclassified from AOCI, HTM |  |  |  |  |  |  |  |  | 377,000 | 844,000 | 1,025,000
OCI before reclassifications, Defined Benefit Pension and Post Retirement Plans |  |  |  |  |  |  |  |  | 1,585,000 | (35,189,000) | 38,775,000
Amounts reclassified from AOCI,All other |  |  |  |  |  |  |  |  | (9,110,000) | (18,762,000) | (15,301,000)
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax |  |  |  |  |  |  |  |  | 6,185,000 | (33,953,000) | 41,635,000
Other comprehensive loss | $ (3,386,000) | $ 6,290,000 | $ (35,944,000) | 3,827,000 | $ (29,337,000) | $ (18,887,000) | $ 26,483,000 | $ 16,678,000 | (29,213,000) | (5,063,000) | (29,189,000)
Balance December, | (9,425,000) |  |  |  | 19,788,000 |  |  |  | (9,425,000) | 19,788,000 |
Accumulated Other-than-Temporary Impairment [Member] |  |  |  |  |  |  |  |  |  |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |  |  |  |  |  |  |  |  |  |
Balance December, |  |  |  | (514,000) |  |  |  | (1,599,000) | (514,000) | (1,599,000) |
OCI before reclassifications |  |  |  |  |  |  |  |  | 0 | 0 |
Other comprehensive loss |  |  |  |  |  |  |  |  | 232,000 | 1,085,000 |
Balance December, | (282,000) |  |  |  | (514,000) |  |  |  | (282,000) | (514,000) | (1,599,000)
Accumulated Defined Benefit Plans Adjustment [Member] |  |  |  |  |  |  |  |  |  |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |  |  |  |  |  |  |  |  |  |
Balance December, |  |  |  | (60,605,000) |  |  |  | (26,652,000) | (60,605,000) | (26,652,000) |
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax |  |  |  |  |  |  |  |  | 4,600,000 | 1,236,000 |
Balance December, | (54,420,000) |  |  |  | (60,605,000) |  |  |  | (54,420,000) | (60,605,000) | (26,652,000)
Accumulated other comprehensive income (loss) [Member] |  |  |  |  |  |  |  |  |  |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |  |  |  |  |  |  |  |  |  |
Balance December, |  |  |  | 19,788,000 |  |  |  | 24,851,000 | 19,788,000 | 24,851,000 |
OCI before reclassifications |  |  |  |  |  |  |  |  | (24,558,000) | 12,222,000 |
Amount reclassified from AOCI |  |  |  |  |  |  |  |  | (4,655,000) | (17,285,000) |
Other comprehensive loss |  |  |  |  |  |  |  |  | (29,213,000) | (5,063,000) | (29,189,000)
Balance December, | (9,425,000) |  |  |  | 19,788,000 |  |  |  | (9,425,000) | 19,788,000 | 24,851,000
Held-to-maturity Securities [Member] | Accumulated Net Unrealized Investment Gain (Loss) [Member] |  |  |  |  |  |  |  |  |  |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |  |  |  |  |  |  |  |  |  |
Balance December, |  |  |  | 623,000 |  |  |  | 1,467,000 | 623,000 | 1,467,000 |
OCI before reclassifications |  |  |  |  |  |  |  |  | 0 | 0 |
Other comprehensive loss |  |  |  |  |  |  |  |  | (377,000) | (844,000) |
Balance December, | 246,000 |  |  |  | 623,000 |  |  |  | 246,000 | 623,000 | 1,467,000
Available-for-sale Securities [Member] |  |  |  |  |  |  |  |  |  |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |  |  |  |  |  |  |  |  |  |
Balance December, |  |  |  | 80,284,000 |  |  |  | 51,635,000 | 80,284,000 | 51,635,000 |
OCI before reclassifications |  |  |  |  |  |  |  |  | (26,143,000) | 47,411,000 |
Other comprehensive loss |  |  |  |  |  |  |  |  | (35,253,000) | 28,649,000 |
Balance December, | 45,031,000 |  |  |  | 80,284,000 |  |  |  | 45,031,000 | 80,284,000 | 51,635,000
Investments [Member] |  |  |  |  |  |  |  |  |  |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |  |  |  |  |  |  |  |  |  |
Balance December, |  |  |  | $ 80,393,000 |  |  |  | $ 51,503,000 | 80,393,000 | 51,503,000 |
OCI before reclassifications |  |  |  |  |  |  |  |  | (26,143,000) | 47,411,000 |
Amount reclassified from AOCI |  |  |  |  |  |  |  |  | (9,255,000) | (18,521,000) |
Other comprehensive loss |  |  |  |  |  |  |  |  | (35,398,000) | 28,890,000 |
Balance December, | $ 44,995,000 |  |  |  | $ 80,393,000 |  |  |  | $ 44,995,000 | $ 80,393,000 | $ 51,503,000

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