Fair Value (Narrative) (Details) (USD $)	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010
Fair Value, Measurements, Recurring [Member]
Transfers from Level 1 to Level 2	$ 0	$ 0
Transfers from Level 2 to Level 1	0	0
Fair Value, Measurements, Nonrecurring [Member]
Significant fair value adjustments for assets and liabilities measured on a nonrecurring basis	0	0
AARP Program [Member] \| Fair Value, Measurements, Recurring [Member]
Transfers from Level 1 to Level 2	0	0
Transfers from Level 2 to Level 1	0	0
Equity Securities [Member] \| Fair Value, Measurements, Recurring [Member]
Available for sale securities fair value disclosure	544,000,000	516,000,000
Equity Securities [Member] \| AARP Program [Member] \| Fair Value, Measurements, Recurring [Member]
Available for sale securities fair value disclosure	2,000,000	2,000,000
Equity Securities [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Measurements, Recurring [Member]
Available for sale securities fair value disclosure	209,000,000	208,000,000
Equity Securities [Member] \| Fair Value, Inputs, Level 3 [Member] \| AARP Program [Member] \| Fair Value, Measurements, Recurring [Member]
Available for sale securities fair value disclosure	0	0
Venture Capital Funds [Member] \| Equity Securities [Member] \| Fair Value, Inputs, Level 3 [Member]
Fair values of Level 3 investments in venture capital portfolios	168,000,000	166,000,000
Preferred Stock And Other Items With No Active Markets [Member] \| Equity Securities [Member] \| Fair Value, Inputs, Level 3 [Member]
Available for sale securities fair value disclosure	$ 41,000,000	$ 42,000,000

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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