Fair Value (Financial Assets and Liabilities, Excluding AARP, Measured at Fair Value on a Recurring Basis) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Cash and cash equivalents	$ 7,276	$ 8,406
Available-for-sale Securities, Debt Securities	19,427
Available-for-sale Securities, Equity Securities	1,572	677
Interest rate swap assets		14
Total assets at fair value	28,275	28,323
Percentage of total assets at fair value	100.00%	100.00%
Interest rate and currency swap liabilities		14
Interest rate swap liabilities	163
Debt Securities [Member]
Available-for-sale Securities, Debt Securities	19,427	19,226
U.S. Government and Agency Obligations [Member]
Available-for-sale Securities, Debt Securities	2,195	2,538
State and Municipal Obligations [Member]
Available-for-sale Securities, Debt Securities	6,977	6,667
Corporate Obligations [Member]
Available-for-sale Securities, Debt Securities	7,335	7,209
U.S. Agency Mortgage-Backed Securities [Member]
Available-for-sale Securities, Debt Securities	2,218	2,238
Non-U.S. Agency Mortgage-Backed Securities [Member]
Available-for-sale Securities, Debt Securities	702	574
Quoted Prices in Active Markets (Level 1) [Member]
Cash and cash equivalents	7,005	7,615
Available-for-sale Securities, Equity Securities	1,291	450
Interest rate swap assets		0
Total assets at fair value	10,071	9,830
Percentage of total assets at fair value	36.00%	35.00%
Interest rate and currency swap liabilities		0
Interest rate swap liabilities	0
Quoted Prices in Active Markets (Level 1) [Member] \| Debt Securities [Member]
Available-for-sale Securities, Debt Securities	1,775	1,765
Quoted Prices in Active Markets (Level 1) [Member] \| U.S. Government and Agency Obligations [Member]
Available-for-sale Securities, Debt Securities	1,750	1,752
Quoted Prices in Active Markets (Level 1) [Member] \| State and Municipal Obligations [Member]
Available-for-sale Securities, Debt Securities	0	0
Quoted Prices in Active Markets (Level 1) [Member] \| Corporate Obligations [Member]
Available-for-sale Securities, Debt Securities	25	13
Quoted Prices in Active Markets (Level 1) [Member] \| U.S. Agency Mortgage-Backed Securities [Member]
Available-for-sale Securities, Debt Securities	0	0
Quoted Prices in Active Markets (Level 1) [Member] \| Non-U.S. Agency Mortgage-Backed Securities [Member]
Available-for-sale Securities, Debt Securities	0	0
Other Observable Inputs (Level 2) [Member]
Cash and cash equivalents	271	791
Available-for-sale Securities, Equity Securities	12	3
Interest rate swap assets		14
Total assets at fair value	17,893	18,252
Percentage of total assets at fair value	63.00%	64.00%
Interest rate and currency swap liabilities		14
Interest rate swap liabilities	163
Other Observable Inputs (Level 2) [Member] \| Debt Securities [Member]
Available-for-sale Securities, Debt Securities	17,610	17,444
Other Observable Inputs (Level 2) [Member] \| U.S. Government and Agency Obligations [Member]
Available-for-sale Securities, Debt Securities	445	786
Other Observable Inputs (Level 2) [Member] \| State and Municipal Obligations [Member]
Available-for-sale Securities, Debt Securities	6,977	6,667
Other Observable Inputs (Level 2) [Member] \| Corporate Obligations [Member]
Available-for-sale Securities, Debt Securities	7,274	7,185
Other Observable Inputs (Level 2) [Member] \| U.S. Agency Mortgage-Backed Securities [Member]
Available-for-sale Securities, Debt Securities	2,218	2,238
Other Observable Inputs (Level 2) [Member] \| Non-U.S. Agency Mortgage-Backed Securities [Member]
Available-for-sale Securities, Debt Securities	696	568
Unobservable Inputs (Level 3) [Member]
Cash and cash equivalents	0	0
Available-for-sale Securities, Equity Securities	269	224
Interest rate swap assets		0
Total assets at fair value	311	241
Percentage of total assets at fair value	1.00%	1.00%
Interest rate and currency swap liabilities		0
Interest rate swap liabilities	0
Unobservable Inputs (Level 3) [Member] \| Debt Securities [Member]
Available-for-sale Securities, Debt Securities	42	17
Unobservable Inputs (Level 3) [Member] \| U.S. Government and Agency Obligations [Member]
Available-for-sale Securities, Debt Securities	0	0
Unobservable Inputs (Level 3) [Member] \| State and Municipal Obligations [Member]
Available-for-sale Securities, Debt Securities	0	0
Unobservable Inputs (Level 3) [Member] \| Corporate Obligations [Member]
Available-for-sale Securities, Debt Securities	36	11
Unobservable Inputs (Level 3) [Member] \| U.S. Agency Mortgage-Backed Securities [Member]
Available-for-sale Securities, Debt Securities	0	0
Unobservable Inputs (Level 3) [Member] \| Non-U.S. Agency Mortgage-Backed Securities [Member]
Available-for-sale Securities, Debt Securities	$ 6	$ 6

Assets Measured at Fair Value on a Recurring Basis as a Percentage of Total Assets at Fair Value

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- Definition

This element represents the aggregate of the assets reported on the balance sheet at period end measured at fair value on a recurring basis by the entity. This element is intended to be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements.

+ References

No definition available.

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- Definition

Amount of debt securities categorized neither as held-to-maturity nor trading.

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Amount of equity securities categorized neither as held-to-maturity nor as trading.

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- Definition

Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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-Glossary Cash Equivalents

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Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

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Fair value as of the balance sheet date of interest rate derivative assets, which includes all such derivative instruments in hedging and nonhedging relationships that are recognized as assets.

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Fair value as of the balance sheet date of interest rate derivative liabilities, which includes all such derivative instruments in hedging and nonhedging relationships that are recognized as liabilities.

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