Securities (Amortized Cost and Estimated Fair Value of Securities, Excluding Trading Securities, Presented by Contractual Maturity) (Details) (USD $) In Thousands	Jun. 30, 2011	Dec. 31, 2010	Jun. 30, 2010
Securities
Held to Maturity, Due in one year or less, Amortized Cost
Held to Maturity, Due after one year through five years, Amortized Cost	1,000
Held to Maturity, Due after five years through ten years, Amortized Cost	250,953
Held to Maturity, Due after ten years, Amortized Cost	93,941
Held to Maturity, Due in one year or less, Estimated Fair Value
Held to Maturity, Due after one year through five years, Estimated Fair Value	1,000
Held to Maturity, Due after five through ten years, Estimated Fair Value	270,674
Held to Maturity, Due after ten years, Estimated Fair Value	95,033
Residential mortgage-backed securities, Held to Maturity, Estimated Fair Value	4,268
Residential mortgage-backed Securities, Held To Maturity, Amortized Cost	4,103
Equity securities, Held to Maturity, Amortized Cost
Equity securities, Held to Maturity, Estimated Fair Value
Held to Maturity, Amortized Cost	349,997	283,629	252,995
Held to Maturity, Estimated Fair Value	370,975	296,228
Available for Sale, Due in one year or less, Amortized Cost	44,715
Available for Sale, Due after one year through five years, Amortized Cost	829,948
Available for Sale, Due after five years through ten years, Amortized Cost	172,958
Available for Sale, Due after ten years, Amortized Cost	1,751,857
Residential mortgage-backed securities, Available For Sale, Amortized Cost	2,356,226
Equity securities, Available for Sale, Amortized Cost	37,980
Available for Sale, Due in one year or less, Estimated Fair Value	45,289
Available for Sale, Due after one year through five years, Estimated Fair Value	854,447
Available for Sale, Due after five years through ten years, Estimated Fair Value	182,651
Available for Sale, Due after ten years, Estimated Fair Value	1,827,324
Residential mortgage-backed securities, Available for Sale, Estimated Fair Value	2,484,663
Equity securities, Available for Sale, Estimated Fair Value	37,980
Available for Sale, Amortized Cost	5,193,684	5,009,759
Available for Sale, Estimated Fair Value	$ 5,432,354	$ 5,157,470	$ 4,753,608

Mortgage-backed securities Available For Sale, Amortized Cost

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Mortgage Backed Securities Held To Maturity Net Carrying Amount

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Securities

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For an unclassified balance sheet, this item represents investments in debt and equity securities which are categorized neither as held-to-maturity nor trading. Such securities are reported at fair value, with unrealized gains and losses excluded from earnings and reported in a separate component of shareholders' equity (other comprehensive income), unless the Available-for-sale Security is designated as a hedge or is determined to have had an other than temporary decline in fair value below its amortized cost basis. All or a portion of the unrealized holding gain or loss of an Available-for-sale Security that is designated as being hedged in a fair value hedge shall be recognized in earnings during the period of the hedge, as should other than temporary declines in fair value below costs basis.

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-Name Statement of Financial Accounting Standard (FAS)
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This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments made for accretion, amortization, other-than-temporary impairments, and hedging, if any.

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This item represents debt securities, at cost, net of adjustments made for accretion, amortization, other-than-temporary impairments, and hedging, if any, which are expected to mature after five years and through ten years from the balance sheet date and which are categorized neither as held-to-maturity nor trading securities.

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This item represents the fair value of debt securities which are expected to mature after five years and through ten years from the balance sheet date and which are categorized neither as held-to-maturity nor trading securities.

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-Paragraph 20
-Subparagraph c

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This item represents debt securities, at cost, net of adjustments made for accretion, amortization, other-than-temporary impairments, and hedging, if any, which are expected to mature after one year and through five years from the balance sheet date and which are categorized neither as held-to-maturity nor trading securities.

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This item represents the fair value of debt securities which are expected to mature after one year and through five years from the balance sheet date and which are categorized neither as held-to-maturity nor trading securities.

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This item represents debt securities, at cost, net of adjustments made for accretion, amortization, other-than-temporary impairments, and hedging, if any, which are expected to mature after ten years from the balance sheet date and which are categorized neither as held-to-maturity nor trading securities.

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This item represents the fair value of debt securities which are expected to mature after ten years from the balance sheet date which are categorized neither as held-to-maturity nor trading securities.

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This item represents debt securities, at cost, net of adjustments made for accretion, amortization, other-than-temporary impairments, and hedging, if any, which are expected to mature within one year of the balance sheet date and which are categorized neither as held-to-maturity nor trading securities.

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This item represents the fair value of debt securities which are expected to mature within one year of the balance sheet date and which are categorized neither as held-to-maturity nor trading securities.

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-Publisher FASB
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This item represents debt securities, categorized neither as held-to-maturity nor trading securities, which do not have a single maturity date and which the Company has decided to disclose separately rather than allocating such cost, net of adjustments made for accretion, amortization, other-than-temporary impairments, and hedging, if any, over several maturity groupings.

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This item represents the fair value of debt securities, categorized neither as held-to-maturity nor trading securities, which do not have a single maturity date and which the Company has decided to disclose separately, rather than allocating such cost over several maturity groupings.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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For an unclassified balance sheet, this item represents investments in debt securities which are categorized as held-to-maturity; such investments are measured at amortized cost (carrying value). The held-to-maturity category is for those securities that the Entity has the positive intent and ability to hold until maturity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 43
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-Section A
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This item represents the fair value of debt securities which are expected to mature after five years and through ten years from the balance sheet date and which are categorized as held-to-maturity.

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-Publisher FASB
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This item represents the fair value of debt securities which are expected to mature after one year and through five years from the balance sheet date and which are categorized as held-to-maturity.

+ References

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-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
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This item represents debt securities, at cost, net of adjustments made for accretion, amortization, other-than-temporary impairments, and hedging, if any, which are expected to mature after one year and through five years from the balance sheet date and which are categorized as held-to-maturity.

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This item represents the fair value of debt securities which are expected to mature after ten years from the balance sheet date 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)
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This item represents debt securities, at cost, net of adjustments made for accretion, amortization, other-than-temporary impairments, and hedging, if any, which are expected to mature after ten years from the balance sheet date and which are categorized as held-to-maturity.

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This item represents the fair value of debt securities which are expected to mature within one year 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 20
-Subparagraph a

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This item represents debt securities, at cost, net of adjustments made for accretion, amortization, other-than-temporary impairments, and hedging, if any, which are expected to mature within one year of the balance sheet date and which are categorized as held-to-maturity.

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This item represents the fair value of debt securities categorize as held-to-maturity which do not have a single maturity date and which the Company has decided to disclose separately, rather than allocating such cost over several maturity groupings.

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This item represents debt securities categorized as held-to-maturity which do Not have a single maturity date and which the Company has decided to disclose separately rather than allocating such cost, net of adjustments made for accretion, amortization, other-than-temporary impairments, and hedging, if any, over several maturity groupings.

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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)
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- Definition

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents securitized, pay-through debt securities collateralized by real estate mortgage loans (mortgages) as of the balance sheet date which have been categorized as available-for-sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Audit and Accounting Guide (AAG)
-Number AAG-DEP
-Chapter 7
-Paragraph 15
-IssueDate 2006-05-01

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