Investment Securities (Investment Securities, at Fair Value) (Details) (USD $) In Thousands	Jun. 30, 2011	Dec. 31, 2010
Available for sale securities	$ 7,717,634	$ 7,294,303
Trading securities	32,074	11,710
Non-marketable	109,867	103,521
Total investment securities	7,859,575	7,409,534
U.S. Government and Federal Agency Obligations [Member]
Available for sale securities	356,246	455,537
Government-Sponsored Enterprise Obligations [Member]
Available for sale securities	264,553	201,895
State and Municipal Obligations [Member]
Available for sale securities	1,193,561	1,119,485
Agency Mortgage-Backed Securities [Member]
Available for sale securities	2,913,805	2,491,199
Non-Agency Mortgage-Backed Securities [Member]
Available for sale securities	385,937	455,790
Other Asset-Backed Securities [Member]
Available for sale securities	2,394,627	2,354,260
Other Debt Securities [Member]
Available for sale securities	168,859	176,964
Equity Securities [Member]
Available for sale securities	$ 40,046	$ 39,173

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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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 Trading Securities which consist of all investments in certain debt and equity securities that are bought and held principally for the purpose of selling them in the near term (thus held for only a short period of time) or for which an entity has elected the fair value option. Trading generally reflects active and frequent buying and selling, and trading securities are generally used with the objective of generating profits on short-term differences in price, but this category of investments may also include items which are not intended to be sold in the near term or for which the fair value option has been elected.

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