Investment Securities (Investment Securities, At Fair Value) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities	$ 9,522,248	$ 9,224,702
Trading securities	28,837	17,853
Non-marketable securities	118,650	115,832
Total investment securities	9,669,735	9,358,387
U.S. government and federal agency obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities	438,759	364,665
Government-sponsored enterprise obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities	471,574	315,698
State and municipal obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities	1,615,707	1,245,284
Agency mortgage-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities	3,380,955	4,106,059
Non-agency mortgage-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities	237,011	316,902
Other asset-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities	3,167,394	2,693,143
Other debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities	177,752	141,260
Equity securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities	$ 33,096	$ 41,691

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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+ Details

- 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 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.

+ References+ Details