Investment Securities (Details 1) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Amortized cost and fair values of investment securities available for sale by contractual maturity
Due in one year or less, Amortized cost	$ 63,147
Due after one year through five years, Amortized cost	180,450
Due after five years through ten years, Amortized cost	557,997
Due after ten years, Amortized cost	86,899
Total debt securities, Amortized cost	888,493
Amortized Cost	4,775,400	6,011,976
Due in one year or less, Fair value	64,313
Due after one year through five years, Fair value	185,425
Due after five years through ten years, Fair value	595,889
Due after ten years, Fair value	91,199
Total debt securities, Fair value	936,826
Investment securities available for sale, at fair value	4,937,483	6,101,341
Residential mortgage-related securities
Amortized cost and fair values of investment securities available for sale by contractual maturity
Amortized Cost	3,674,696	4,831,481
Investment securities available for sale, at fair value	3,785,590	4,910,497
Commercial mortgage-related securities
Amortized cost and fair values of investment securities available for sale by contractual maturity
Amortized Cost	16,647	7,604
Investment securities available for sale, at fair value	18,543	7,753
Asset-backed securities
Amortized cost and fair values of investment securities available for sale by contractual maturity
Amortized Cost	188,439	299,459
Investment securities available for sale, at fair value	187,732	298,841
Equity Securities
Amortized cost and fair values of investment securities available for sale by contractual maturity
Amortized Cost	7,125
Investment securities available for sale, at fair value	$ 8,792

This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

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For an unclassified balance sheet, total of debt securities categorized neither as held-to-maturity nor trading.

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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 Available-for-sale Securities which consist of all investments in certain debt and equity securities neither classified as trading or held-to-maturity securities. A debt security represents a creditor relationship with an enterprise. Debt securities include, among other items, US Treasury securities, US government securities, municipal securities, corporate bonds, convertible debt, commercial paper, and all securitized debt instruments. An equity security represents an ownership interest in an enterprise or the right to acquire or dispose of an ownership interest in an enterprise at fixed or determinable prices. Equity securities include, among other things, common stock, certain preferred stock, warrant rights, call options, and put options, but do not include convertible debt. An entity may opt to provide the reader with additional narrative text to better understand the nature of investments in debt and equity securities which are categorized as Available-for-sale.

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