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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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.

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Investment Securities (Details 3) (USD $)	3 Months Ended	6 Months Ended
Investment Securities (Details 3) (USD $)	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010
Available-for-Sale:
Amortized Cost		$ 4,047,351,000		$ 6,457,151,000
Fair Value		4,112,601,000		6,533,874,000
Held-to-Maturity:
Amortized Cost		2,512,024,000		127,249,000
Fair Value		2,566,621,000		134,028,000
Carrying value of investment securities which are pledged		3,200,000,000		3,200,000,000
Gross gains on sale of investment securities	15,000,000	10,300,000	35,000,000
Gross losses on sale of investment securities		4,200,000
Debt Securities Issued by the U.S. Treasury and Government Agencies
Available-for-Sale:
Amortized Cost		1,016,715,000		536,770,000
Fair Value		1,023,753,000		555,856,000
Held-to-Maturity:
Amortized Cost		179,489,000
Fair Value		183,068,000
Mortgage-Backed Securities Issued by Government Agencies
Available-for-Sale:
Amortized Cost		2,783,398,000		5,696,907,000
Fair Value		2,835,051,000		5,750,028,000
Held-to-Maturity:
Amortized Cost		2,270,256,000		47,368,000
Fair Value		2,317,949,000		50,327,000
Mortgage-Backed Securities Issued by U.S. Government-Sponsored Enterprises
Available-for-Sale:
Amortized Cost		76,385,000		109,259,000
Fair Value		79,916,000		113,876,000
Held-to-Maturity:
Amortized Cost		62,279,000		79,881,000
Fair Value		65,604,000		83,701,000
Mortgage-Backed Securities
Available-for-Sale:
Amortized Cost		2,859,783,000		5,806,166,000
Fair Value		2,914,967,000		5,863,904,000
Held-to-Maturity:
Amortized Cost		2,332,535,000
Fair Value		$ 2,383,553,000