Investments (Investment Gains and Losses) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended	12 Months Ended
Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Held to maturity debt securities:
Real estate gains (losses)	$ 2,644	$ 0	$ 2,485	$ (50)
Mortgage loans write-downs	0	0	0	(39)
Other	12	0	12	0
Totals	5,451	2,960	9,242	6,542
Percentage of gains on bonds, due to calls of securities			77.00%
Total other-than-temporary impairment gains (losses) on debt securities	1,267	(1,727)	858	(1,727)
Portion of loss (gain) recognized in comprehensive income	(1,761)	1,719	(1,918)	1,719
Net impairment losses (gains) on debt securities recognized in earnings	(494)	(8)	(1,060)	(8)
Equity securities impairments	(17)	(14)	(70)	(14)
Net OTTI losses recognized in earnings	(511)	(22)	(1,130)	(22)
Non-Credit Other-than-Temporary Impairment, Credit Losses Recognized in Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance, cumulative credit losses related to other-than-temporary impairments	1,688		1,122	997	997
Additions for credit losses not previously recognized in other-than-temporary impairments	494		1,060		125
Ending balance, cumulative credit losses related to other-than-temporary impairments	2,182		2,182		1,122
New Orleans Property Impaired by Hurricane Katrina [Member]
Held to maturity debt securities:
Real estate gains (losses)	(2,600)
Debt Securities [Member]
Held to maturity debt securities:
Realized gains on disposal	1,102	269	1,262	747
Realized losses on disposal	(267)	(520)	(680)	(520)
Debt Securities [Member]
Available for sale debt securities:
Realized gains on disposal	1,847	3,211	6,054	6,348
Realized losses on disposal	0	0	0	0
Equity Securities [Member]
Held to maturity debt securities:
Equity securities realized gains (losses)	$ 113	$ 0	$ 109	$ 56

Held-to-maturity Securities, Realized Gains on Disposal

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Held-to-maturity Securities, Realized Losses on Disposal

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Investments, Percentage of Gains on Bonds, Due to Calls of Securities

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Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net, Debt Securities

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This item represents the gross profit realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities.

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This item represents the net total realized and unrealized gain (loss) included in earnings for the period as a result of selling or holding marketable securities categorized as trading, available-for-sale, or held-to-maturity, including the unrealized holding gain (loss) of held-to-maturity securities transferred to the trading security category and the cumulative unrealized gain (loss) which was included in other comprehensive income (a separate component of shareholders' equity) for available-for-sale securities transferred to trading securities during the period. Additionally, this item would include any gains (losses) realized during the period from the sale of investments accounted for under the cost method of accounting.

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The difference between the carrying value and the sale price of equity securities, not separately or otherwise categorized as trading or available-for-sale. This element includes investments in which the entity holds a small ownership stake (generally, less than 20% of the shares outstanding) and cannot exert significant influence.

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The difference between the book value and the sale price of other nonspecific investments. This element is used when other, more specific, elements are not appropriate. This element refers to the gain (loss) included in earnings.

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The amount of any write-down or reserve provided in the period on a mortgage loan on real estate.

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This item represents an increase to the cumulative amount of credit losses recognized in earnings for an other than temporary impairment (OTTI) of a debt security held for which no such other than temporary impairment (OTTI) was previously recognized.

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The cumulative amount of credit losses recognized in earnings related to debt securities held for which a portion of an other than temporary impairment (OTTI) was recognized in other comprehensive income (a component of shareholders' equity).

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The amount of other than temporary impairment (OTTI) losses on equity securities, OTTI related to credit losses on debt securities, and OTTI losses on debt securities when the entity intends to sell the securities or it is more likely than not that the entity will be required to sell the securities before recovery of its amortized cost basis. Additionally, this item includes OTTI losses recognized during the period on investments accounted for under the cost method of accounting.

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