| **Other Comprehensive Income Other Comprehensive Income** | 6 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |
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| **Equity [Abstract]**                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
| Other Comprehensive Income                                | Other Comprehensive Income (Loss)The following table summarizes activity in the unrealized gain or loss on available for sale securities included in other comprehensive income for the six-months and quarters ended June 30, 2013 and 2012. For the six months ended        June 30, For the quarters ended          June 30, 2013 2012 2013 2012Balance at beginning of period$7,940,000 $7,401,000 $5,474,000 $7,088,000Unrealized gains (losses) arising during the period(16,410,000) 2,159,000 (12,915,000) 2,118,000Reclassification of realized gains during the period(1,087,000) (1,967,000) (788,000) (1,444,000)Related deferred taxes6,124,000 (67,000) 4,796,000 (236,000)Net change(11,373,000) 125,000 (8,907,000) 438,000Balance at end of period$(3,433,000) $7,526,000 $(3,433,000) $7,526,000The reclassification of realized gains is included in the net securities gain line of the consolidated statements of income and comprehensive income and the tax effect is included in the income tax expense line of the same statement.The following table summarizes activity in the unrealized gain or loss on postretirement benefits included in other comprehensive income for the six-months and quarters ended June 30, 2013 and 2012. For the six months endedJune 30, For the quarters endedJune 30, 2013 2012 2013 2012Unrecognized postretirement benefits at beginning of period$(123,000) $(87,000) $(119,000) $(82,000)Amortization of unrecognized transition obligation5,000 14,000 — 7,000Change in accumulated losses4,000 — 6,000 —Related deferred taxes(1,000) (4,000) (2,000) (2,000)Unrecognized postretirement benefits at end of period$(115,000) $(77,000) $(115,000) $(77,000)The reclassification of unrecognized transition obligation is a component of net periodic benefit cost (see Note 8) and the income tax effect is included in the income tax expense line of the consolidated statements of income and comprehensive income. |

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