Debt (Details) (USD $)	9 Months Ended					9 Months Ended	3 Months Ended	9 Months Ended		3 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012 4.000% senior notes due 2017 [Member]	Sep. 30, 2012 5.125% senior notes due 2022 [Member]	Sep. 30, 2012 6.625% senior notes due 2042 [Member]	Sep. 30, 2012 Senior Notes [Member]	Sep. 30, 2012 10.0% Notes, due 2068 [Member]	Sep. 30, 2012 10.0% Notes, due 2068 [Member]	Sep. 30, 2012 6.1% senior notes due 2041 [Member]	Sep. 30, 2012 7.878% fixed-to-floating rate junior subordinated debentures due 2042 [Member]	Sep. 30, 2012 8.125% fixed-to-floating rate junior subordinated debentures due 2068 [Member]	Sep. 30, 2012 Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Maximum amount available under the line of credit facility												$ 1,750,000,000
Line of credit facility maximum borrowing capacity available to support letters of credit												250,000,000
Consolidated total debt to consolidated total capitalization ratio												0.35
Consolidated total debt of subsidiaries to consolidated total capitalization ratio												10.00%
Repurchased of 10% Debentures	2,133,000,000							2,125,000,000
Principal Amount							1,750,000,000
Debt Instrument Face Amount	1,550,000,000		325,000,000	800,000,000	425,000,000					600,000,000
Interest rate on Note			4.00%	5.125%	6.625%		10.00%	10.00%	6.10%	7.875%	8.125%
Debt Instrument, Interest Rate Terms	interest from the date of issuance to but excluding April 15, 2022 at an annual rate of 7.875%, payable quarterly in arrears on January 15, April 15, July 15 and October 15 of each year, commencing on July 15, 2012, to and including April 15, 2022. Commencing on April 15, 2022 the Debentures bear interest at an annual rate equal to three-month LIBOR, reset quarterly, plus 5.596%, payable quarterly in arrears on January 15, April 15, July 15 and October 15 of each year, commencing on July 15, 2022.
Proceed from Long Term Debt	2,123,000,000					1,500,000,000				586,000,000
Net worth after tax												14,900,000,000
Debt (Textual) [Abstract]
Termination of 10% Debentures replacement capital covenant	the 10% Debentures replacement capital covenant (the “10% Debentures RCC”) was terminated on April 12, 2012 with the consent of the holders of a majority in aggregate principal amount of the Company’s outstanding 6.1% senior notes due 2041
Minimum principal amount of debentures remain outstanding after giving effect to redemption	25,000,000
Extinguishment of Debt, Gain (Loss), Net of Tax	$ 587,000,000
Spread rate	0.70%