Invested Assets (Details) (USD $) In Millions	Sep. 30, 2011	Dec. 31, 2010
Amortized cost and fair value of fixed maturities and equity securities [Abstract]
Tax exempt, Amortized cost	$ 18,879	$ 19,072
Tax exempt, Gross unrealized appreciation	1,297	824
Tax exempt, Gross unrealized depreciation	42	122
Tax exempt, Fair value	20,134	19,774
Taxable, Amortized cost	16,337	15,989
Taxable, Gross unrealized appreciation	980	806
Taxable, Gross unrealized depreciation	46	50
Taxable, Fair value	17,271	16,745
Total fixed maturities, Amortized cost	35,216	35,061
Total fixed maturities, Gross unrealized appreciation	2,277	1,630
Total fixed maturities, Gross unrealized depreciation	88	172
Total fixed maturities, Fair value	37,405	36,519
Equity securities, Cost	1,271	1,285
Equity securities, Gross unrealized appreciation	232	340
Equity securities, Gross unrealized depreciation	137	75
Equity securities, Fair value	1,366	1,550
U.S. Government and government agency and authority obligations [Member]
Amortized cost and fair value of fixed maturities and equity securities [Abstract]
Taxable, Amortized cost	812	807
Taxable, Gross unrealized appreciation	50	31
Taxable, Gross unrealized depreciation	2	9
Taxable, Fair value	860	829
Corporate bonds [Member]
Amortized cost and fair value of fixed maturities and equity securities [Abstract]
Taxable, Amortized cost	6,420	6,258
Taxable, Gross unrealized appreciation	449	411
Taxable, Gross unrealized depreciation	31	21
Taxable, Fair value	6,838	6,648
Foreign government and government agency obligations [Member]
Amortized cost and fair value of fixed maturities and equity securities [Abstract]
Taxable, Amortized cost	6,293	5,943
Taxable, Gross unrealized appreciation	372	231
Taxable, Gross unrealized depreciation	6	13
Taxable, Fair value	6,659	6,161
Residential Mortgage-Backed Securities [Member]
Amortized cost and fair value of fixed maturities and equity securities [Abstract]
Taxable, Amortized cost	937	1,293
Taxable, Gross unrealized appreciation	47	63
Taxable, Gross unrealized depreciation	5	6
Taxable, Fair value	979	1,350
Commercial Mortgage-Backed Securities [Member]
Amortized cost and fair value of fixed maturities and equity securities [Abstract]
Taxable, Amortized cost	1,875	1,688
Taxable, Gross unrealized appreciation	62	70
Taxable, Gross unrealized depreciation	2	1
Taxable, Fair value	$ 1,935	$ 1,757

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The excess of the fair value of equity securities over its amortized cost which excess value has not been recognized in earnings of the entity.

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The excess of amortized cost of equity securities over its fair value which deficiency has not been recognized in earnings of the entity.

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The excess of the fair value of fixed maturities over its amortized cost which excess value has not been recognized in earnings of the entity.

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The excess of amortized cost of fixed maturities over its fair value which deficiency has not been recognized in earnings of the entity.

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This item represents total taxable debt securities that are categorized as neither held-to-maturity nor trading. Such securities are reported at fair value; unrealized gains and losses of such securities are excluded from earnings and included in other comprehensive income.

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This item represents the amortized cost basis of taxable debt securities that are categorized as neither held-to-maturity nor trading.

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The excess of the fair value of taxable fixed maturities over its amortized cost which excess value has not been recognized in earnings of the entity.

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The excess of amortized cost of taxable fixed maturities over its fair value which deficiency has not been recognized in earnings of the entity.

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This item represents total tax-exempt debt securities that are categorized as neither held-to-maturity nor trading. Such securities are reported at fair value; unrealized gains and losses of such securities are excluded from earnings and included in other comprehensive income.

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The excess of the fair value of tax exempt fixed maturities over its amortized cost which excess value has not been recognized in earnings of the entity.

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The excess of amortized cost of tax exempt fixed maturities over its fair value which deficiency has not been recognized in earnings of the entity.

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

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