Fair Values of Financial Instruments (Details 1) (USD $) In Millions	Jun. 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	$ 20,164	$ 19,774
Taxable, Fair value	17,203	16,745
Total fixed maturities, Fair value	37,367	36,519
Equity securities, Fair value	1,663	1,550
Total fixed maturities and equity securities	39,030	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, Fair value	1,655	1,537
Total fixed maturities and equity securities	1,655	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	20,156	19,765
Taxable, Fair value	16,992	16,533
Total fixed maturities, Fair value	37,148	36,298
Equity securities, Fair value	0	0
Total fixed maturities and equity securities	37,148	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	832	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	6,666	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	6,516	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	1,092	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	1,886	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	211	212
Total fixed maturities, Fair value	219	221
Equity securities, Fair value	8	13
Total fixed maturities and equity securities	227	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	189	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	6	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	16	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	832	829
Corporate bonds [Member]
Fair values of fixed maturities and equity securities categorized based upon the lowest level of input [Abstract]
Taxable, Fair value	6,855	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	6,522	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	1,108	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	$ 1,886	$ 1,757