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Investments (Held-To-Maturity Securities Disclosure) (Details) (USD $) | 12 Months Ended
--- | ---
Dec. 31, 2012 Securities | Dec. 31, 2011 | Dec. 31, 2010
Amortized Cost | $ 550,143,000 | $ 706,782,000 |
Net Unrealized Gains (Losses) | 3,926,000 | 5,566,000 |
Held-to-maturity Securities | 554,069,000 | 712,348,000 |
Unrecognized Holding Gains | 40,615,000 | 45,946,000 |
Unrecognized Holding Losses | (23,000) | (251,000) |
Fair Value | 594,661,000 | 758,043,000 |
Held To Maturity Securities Average Duration | 2 years 6 months |  |
Number of held to maturity securities transferred to available-for-sale | 10 |  |
Securities reclassified from the HTM category to AFS carrying value | 32,700,000 |  |
Securities reclassified from the HTM category to AFS net unrecognized gain | 2,400,000 |  |
Redemption and maturities of fixed maturity securities, held-to-maturity | 118,260,000 | 177,350,000 | 319,835,000
Foreign Government [Member] |  |  |
Amortized Cost | 5,292,000 | 5,292,000 |
Net Unrealized Gains (Losses) | 212,000 | 292,000 |
Held-to-maturity Securities | 5,504,000 | 5,584,000 |
Unrecognized Holding Gains | 367,000 | 0 |
Unrecognized Holding Losses | 0 | (88,000) |
Fair Value | 5,871,000 | 5,496,000 |
Obligations of States and Political Subdivisions [Member] |  |  |
Amortized Cost | 491,180,000 | 614,118,000 |
Net Unrealized Gains (Losses) | 6,769,000 | 11,894,000 |
Held-to-maturity Securities | 497,949,000 | 626,012,000 |
Unrecognized Holding Gains | 28,996,000 | 31,529,000 |
Unrecognized Holding Losses | (23,000) | (156,000) |
Fair Value | 526,922,000 | 657,385,000 |
Corporate Securities [Member] |  |  |
Amortized Cost | 38,285,000 | 64,840,000 |
Net Unrealized Gains (Losses) | (812,000) | (2,189,000) |
Held-to-maturity Securities | 37,473,000 | 62,651,000 |
Unrecognized Holding Gains | 4,648,000 | 6,887,000 |
Unrecognized Holding Losses | 0 | 0 |
Fair Value | 42,121,000 | 69,538,000 |
Asset-backed Securities [Member] |  |  |
Amortized Cost | 6,980,000 | 8,077,000 |
Net Unrealized Gains (Losses) | (1,052,000) | (1,469,000) |
Held-to-maturity Securities | 5,928,000 | 6,608,000 |
Unrecognized Holding Gains | 1,170,000 | 1,353,000 |
Unrecognized Holding Losses | 0 | (7,000) |
Fair Value | 7,098,000 | 7,954,000 |
Commercial Mortgage Backed Securities [Member] |  |  |
Amortized Cost | 8,406,000 | 14,455,000 |
Net Unrealized Gains (Losses) | (1,191,000) | (2,962,000) |
Held-to-maturity Securities | 7,215,000 | 11,493,000 |
Unrecognized Holding Gains | 5,434,000 | 6,177,000 |
Unrecognized Holding Losses | 0 | 0 |
Fair Value | $ 12,649,000 | $ 17,670,000 |

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- Definition This item represents debt securities categorized as held-to-maturity, at cost, net of adjustments made for amortization and net unrealized gains (losses) resulting from: (i) other-than-temporary impairments and (ii) a previous available-for-sale designation. + References No definition available. + Details
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- Definition As of the balance sheet date, the excess of fair value over carrying value of a debt security categorized as held-to-maturity, exclusive of dividend or interest income recognized but not yet received and exclusive of any write-downs for other-than-temporary impairment. Such item represents the gross unrecognized holding gain. + References No definition available. + Details
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- Definition As of the balance sheet date, the excess of carrying value over fair value of a debt security categorized as held-to-maturity, exclusive of dividend or interest income recognized but not yet received and exclusive of any write-downs for other-than-temporary impairment. Such item represents the gross unrecognized holding loss. + References No definition available. + Details
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- Definition The remaining aggregate increase (decrease) in the market value of held-to-maturity securities either (i) prior to the securities' transfer to a held-to-maturity designation or (ii) resulting from a non-credit other-than-temporary impairment. + References No definition available. + Details
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- Definition This item represents the aggregate fair value of investments in debt securities as of the balance sheet date and which are categorized as held-to-maturity. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 19 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 137 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 5 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27232-111563 + Details
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- Definition For any transfer of securities categorized as held-to-maturity, this item represents the net carrying amount of the transferred security to another category of investments in debt and equity securities (trading or available-for-sale). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 22 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27405-111563 + Details
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- Definition This item represents the unrealized gain (loss) recognized in other comprehensive income (a separate component of shareholders' equity) as a result of securities categorized as held-to-maturity being transferred to the available-for-sale securities category. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27405-111563 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 13, 22 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. + Details
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- Definition The cash inflow associated with the maturity, prepayments and calls (requests for early payments) of debt securities designated as held-to-maturity. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 12 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3179-108585 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 16 -Subparagraph a -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Investing Activities -URI http://asc.fasb.org/extlink&oid=6516133 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 15 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=6871852&loc=d3e26853-111562 + Details
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