Investments (Distribution Of Contractual Maturity Available For Sale) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 8,692	$ 9,025
Fair Value	8,669	8,810
Fixed-Maturity Investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Due in one year or less, Amortized Cost	842
Due in one year or less, Fair Value	844
Due after one year through five years, Amortized Cost	1,131
Due after one year through five years, Fair Value	1,166
Due after five years through ten years, Amortized Cost	719
Due after five years through ten years, Fair Value	746
Due after ten years through fifteen years, Amortized Cost	572
Due after ten years through fifteen years, Fair Value	590
Due after fifteen years, Amortized Cost	1,636
Due after fifteen years, Fair Value	1,682
Amortized Cost	6,787	7,492
Fair Value	6,792	7,336
Fixed-Maturity Investments [Member] \| Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,444
Fair Value	1,432
Fixed-Maturity Investments [Member] \| Asset-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	443
Fair Value	332
Fixed-Maturity Investments [Member] \| Variable Interest Entity [Member]
Schedule of Available-for-sale Securities [Line Items]
Due after one year through five years, Amortized Cost	2
Due after one year through five years, Fair Value	2
Amortized Cost	264
Fair Value	234
Fixed-Maturity Investments [Member] \| Variable Interest Entity [Member] \| Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	114
Fair Value	95
Fixed-Maturity Investments [Member] \| Variable Interest Entity [Member] \| Asset-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	148
Fair Value	$ 137

Available For Sale Securities, Debt Maturities, Due After Fifteen Years, Amortized Cost

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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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