Fair Values of Financial Instruments (Details 1) (USD $) In Millions	Sep. 30, 2011	Dec. 31, 2010
Fair values of fixed maturities and equity securities categorized based upon the lowest level of input [Abstract]
Tax exempt, Fair value	$ 20,134	$ 19,774
Taxable, Fair value	17,271	16,745
Total fixed maturities, Fair value	37,405	36,519
Equity securities	1,366	1,550
Total fixed maturities and equity securities, Fair value	38,771	38,069
Level 1 [Member]
Fair values of fixed maturities and equity securities categorized based upon the lowest level of input [Abstract]
Tax exempt, Fair value	0	0
Taxable, Fair value	0	0
Total fixed maturities, Fair value	0	0
Equity securities	1,358	1,537
Total fixed maturities and equity securities, Fair value	1,358	1,537
Level 1 [Member] \| U.S. Government and government agency and authority obligations [Member]
Fair values of fixed maturities and equity securities categorized based upon the lowest level of input [Abstract]
Taxable, Fair value	0	0
Level 1 [Member] \| Corporate bonds [Member]
Fair values of fixed maturities and equity securities categorized based upon the lowest level of input [Abstract]
Taxable, Fair value	0	0
Level 1 [Member] \| Foreign government and government agency obligations [Member]
Fair values of fixed maturities and equity securities categorized based upon the lowest level of input [Abstract]
Taxable, Fair value	0	0
Level 1 [Member] \| Residential Mortgage-Backed Securities [Member]
Fair values of fixed maturities and equity securities categorized based upon the lowest level of input [Abstract]
Taxable, Fair value	0	0
Level 1 [Member] \| Commercial Mortgage-Backed Securities [Member]
Fair values of fixed maturities and equity securities categorized based upon the lowest level of input [Abstract]
Taxable, Fair value	0	0
Level 2 [Member]
Fair values of fixed maturities and equity securities categorized based upon the lowest level of input [Abstract]
Tax exempt, Fair value	20,126	19,765
Taxable, Fair value	17,080	16,533
Total fixed maturities, Fair value	37,206	36,298
Equity securities	0	0
Total fixed maturities and equity securities, Fair value	37,206	36,298
Level 2 [Member] \| U.S. Government and government agency and authority obligations [Member]
Fair values of fixed maturities and equity securities categorized based upon the lowest level of input [Abstract]
Taxable, Fair value	860	829
Level 2 [Member] \| Corporate bonds [Member]
Fair values of fixed maturities and equity securities categorized based upon the lowest level of input [Abstract]
Taxable, Fair value	6,661	6,483
Level 2 [Member] \| Foreign government and government agency obligations [Member]
Fair values of fixed maturities and equity securities categorized based upon the lowest level of input [Abstract]
Taxable, Fair value	6,656	6,135
Level 2 [Member] \| Residential Mortgage-Backed Securities [Member]
Fair values of fixed maturities and equity securities categorized based upon the lowest level of input [Abstract]
Taxable, Fair value	968	1,329
Level 2 [Member] \| Commercial Mortgage-Backed Securities [Member]
Fair values of fixed maturities and equity securities categorized based upon the lowest level of input [Abstract]
Taxable, Fair value	1,935	1,757
Level 3 [Member]
Fair values of fixed maturities and equity securities categorized based upon the lowest level of input [Abstract]
Tax exempt, Fair value	8	9
Taxable, Fair value	191	212
Total fixed maturities, Fair value	199	221
Equity securities	8	13
Total fixed maturities and equity securities, Fair value	207	234
Level 3 [Member] \| U.S. Government and government agency and authority obligations [Member]
Fair values of fixed maturities and equity securities categorized based upon the lowest level of input [Abstract]
Taxable, Fair value	0	0
Level 3 [Member] \| Corporate bonds [Member]
Fair values of fixed maturities and equity securities categorized based upon the lowest level of input [Abstract]
Taxable, Fair value	177	165
Level 3 [Member] \| Foreign government and government agency obligations [Member]
Fair values of fixed maturities and equity securities categorized based upon the lowest level of input [Abstract]
Taxable, Fair value	3	26
Level 3 [Member] \| Residential Mortgage-Backed Securities [Member]
Fair values of fixed maturities and equity securities categorized based upon the lowest level of input [Abstract]
Taxable, Fair value	11	21
Level 3 [Member] \| Commercial Mortgage-Backed Securities [Member]
Fair values of fixed maturities and equity securities categorized based upon the lowest level of input [Abstract]
Taxable, Fair value	0	0
U.S. Government and government agency and authority obligations [Member]
Fair values of fixed maturities and equity securities categorized based upon the lowest level of input [Abstract]
Taxable, Fair value	860	829
Corporate bonds [Member]
Fair values of fixed maturities and equity securities categorized based upon the lowest level of input [Abstract]
Taxable, Fair value	6,838	6,648
Foreign government and government agency obligations [Member]
Fair values of fixed maturities and equity securities categorized based upon the lowest level of input [Abstract]
Taxable, Fair value	6,659	6,161
Residential Mortgage-Backed Securities [Member]
Fair values of fixed maturities and equity securities categorized based upon the lowest level of input [Abstract]
Taxable, Fair value	979	1,350
Commercial Mortgage-Backed Securities [Member]
Fair values of fixed maturities and equity securities categorized based upon the lowest level of input [Abstract]
Taxable, Fair value	$ 1,935	$ 1,757

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

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

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-Name Accounting Standards Codification

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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

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 3

-Subparagraph c

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

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Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 45

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Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

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-Publisher FASB

-Name Accounting Standards Codification

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-Publisher FASB

-Name Emerging Issues Task Force (EITF)

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+ Details