Investments (States, Municipalities And Political Subdivisions Securities In A Gross Unrealized Loss Position by Ratings Distribution) (Details) (USD $) In Millions	Jun. 30, 2011	Dec. 31, 2010
Amortized Cost	$ 38,004	$ 37,656
Estimated Fair Value	39,849	38,900
Gross Unrealized Losses	567	851
States, Municipalities And Political Subdivisions [Member] \| AAA [Member]
Amortized Cost	412
Estimated Fair Value	387
Gross Unrealized Losses	25
States, Municipalities And Political Subdivisions [Member] \| AA [Member]
Amortized Cost	1,050
Estimated Fair Value	877
Gross Unrealized Losses	173
States, Municipalities And Political Subdivisions [Member] \| A [Member]
Amortized Cost	713
Estimated Fair Value	650
Gross Unrealized Losses	63
States, Municipalities And Political Subdivisions [Member] \| BBB [Member]
Amortized Cost	71
Estimated Fair Value	65
Gross Unrealized Losses	6
States, Municipalities And Political Subdivisions [Member] \| Non-Investment Grade [Member]
Amortized Cost	16
Estimated Fair Value	15
Gross Unrealized Losses	1
Total States, Municipalities And Political Subdivisions Securities [Member]
Amortized Cost	2,262
Estimated Fair Value	1,994
Gross Unrealized Losses	$ 268

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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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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