Fair Values of Financial Instruments (Details) (USD $) In Millions	Sep. 30, 2011	Dec. 31, 2010
Carrying values and fair values of financial instruments [Abstract]
Short term investments	$ 2,289	$ 1,905
Fixed maturities	37,405	36,519
Equity securities	1,366	1,550
Long term debt	3,975	3,975
Carrying Value [Member]
Carrying values and fair values of financial instruments [Abstract]
Short term investments	2,289	1,905
Fixed maturities	37,405	36,519
Equity securities	1,366	1,550
Long term debt	3,975	3,975
Fair Value [Member]
Carrying values and fair values of financial instruments [Abstract]
Short term investments	2,289	1,905
Fixed maturities	37,405	36,519
Equity securities	1,366	1,550
Long term debt	$ 4,427	$ 4,318

For an unclassified balance sheet, total of debt securities categorized neither as held-to-maturity nor trading.

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+ Details

- Definition

For an unclassified balance sheet, this item represents equity securities categorized neither as held-to-maturity nor trading.

+ References

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