Investment Securities (Schedule Of Securities Classified As Current And Long-Term) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Amortized Cost	$ 8,928	$ 8,176
Gross Unrealized Gains	542	259
Gross Unrealized Losses	(17)	(62)
Fair Value	9,453.0	8,373.0
Debt Securities [Member] \| Tax-Exempt Municipal Securities [Member]
Amortized Cost	2,709	2,440
Gross Unrealized Gains	149	37
Gross Unrealized Losses	(2)	(44)
Fair Value	2,856.0	2,433.0
Debt Securities [Member] \| Residential Mortgage-Backed Securities [Member]
Amortized Cost	46	58
Gross Unrealized Gains	0	1
Gross Unrealized Losses	(2)	(3)
Fair Value	44.0	56.0
Debt Securities [Member] \| Commercial Mortgage-Backed Securities [Member]
Amortized Cost	356	306
Gross Unrealized Gains	25	15
Gross Unrealized Losses	0	0
Fair Value	381.0	321.0
Debt Securities [Member] \| Asset-Backed Securities [Member]
Amortized Cost	82	148
Gross Unrealized Gains	1	2
Gross Unrealized Losses	0	0
Fair Value	83.0	150.0
Debt Securities [Member] \| Corporate Debt Securities [Member]
Amortized Cost	3,329	2,906
Gross Unrealized Gains	262	140
Gross Unrealized Losses	(11)	(14)
Fair Value	3,580.0	3,032.0
Debt Securities [Member] \| Redeemable Preferred Stock [Member]
Amortized Cost		5
Gross Unrealized Gains		0
Gross Unrealized Losses		0
Fair Value		5.0
Debt Securities [Member] \| U.S. Treasury And Other U.S. Government Corporations And Agencies [Member] \| U.S. Treasury And Agency Obligations [Member]
Amortized Cost	705	698
Gross Unrealized Gains	20	14
Gross Unrealized Losses	0	0
Fair Value	725.0	712.0
Debt Securities [Member] \| U.S. Treasury And Other U.S. Government Corporations And Agencies [Member] \| Mortgage-Backed Securities [Member]
Amortized Cost	1,701	1,615
Gross Unrealized Gains	85	50
Gross Unrealized Losses	(2)	(1)
Fair Value	$ 1,784.0	$ 1,664.0

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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- Definition

This item represents the gross unrealized gains for securities, at a point in time, which are categorized neither as held-to-maturity nor trading securities.

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