Investment Securities (Summary Of Agency Securities Estimated Weighted Average Life Classifications) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2012 years	Dec. 31, 2011 years
Weighted Average Life of Interest Only Securities	5.7	3.0
Agency securities classified as available for sale, Fair value	$ 84,699	$ 54,504
Agency securities classified as available for sale, Amortized cost	82,652	53,503
Weighted average coupon	3.59%	4.11%
Available For Sale Securities Weighted Average Life yield	2.59%	3.05%
Weighted Average Life Of Principal Only Securities	6.4	2.6
Less Than or Equal to One Year [Member]
Available For Sale Securities Weighted Average Life Fair Value	0	214
Available For Sale Securities Weighted Average Life Amortized Cost	0	210
Weighted average coupon	0.00%	4.61%
Available For Sale Securities Weighted Average Life yield	0.00%	3.51%
Greater Than One Year and Less Than or Equal to Three Years [Member]
Available For Sale Securities Weighted Average Life Fair Value	1,119	3,392
Available For Sale Securities Weighted Average Life Amortized Cost	1,108	3,338
Weighted average coupon	4.18%	4.38%
Available For Sale Securities Weighted Average Life yield	2.14%	2.54%
Greater Than Three Years and Less Than or Equal to Five Years [Member]
Available For Sale Securities Weighted Average Life Fair Value	27,448	26,168
Available For Sale Securities Weighted Average Life Amortized Cost	26,750	25,616
Weighted average coupon	3.36%	3.99%
Available For Sale Securities Weighted Average Life yield	2.29%	2.89%
Greater Than Five Years [Member]
Available For Sale Securities Weighted Average Life Fair Value	54,054	24,710
Available For Sale Securities Weighted Average Life Amortized Cost	52,735	24,320
Weighted average coupon	3.69%	4.19%
Available For Sale Securities Weighted Average Life yield	2.75%	3.29%
Greater Than Ten Years [Member]
Available For Sale Securities Weighted Average Life Fair Value	2,078	20
Available For Sale Securities Weighted Average Life Amortized Cost	$ 2,059	$ 19
Weighted average coupon	3.44%	5.02%
Available For Sale Securities Weighted Average Life yield	2.65%	2.12%

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.

+ References+ Details

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.

+ References+ Details