Debt (Details) (USD $)	3 Months Ended
	Mar. 31, 2012	Dec. 31, 2011
Debt Instrument [Line Items]
Debt Instrument Face Amount	$ 1,550,000,000
Debt instrument, Frequency of periodic payments	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
Proceed from Long Term Debt	1,500,000,000
Debt (Textual) [Abstract]
Termination of 10% Debentures replacement capital covenant	the 10% Debentures replacement capital covenant (the “10% Debentures RCC”) was terminated on April __, 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
Loss on extinguishment	600,000,000
Minimum principal amount of debentures remain outstanding after giving effect to redemption	25,000,000
Spread rate	0.70%
4.000% senior notes due 2017 [Member]
Debt Instrument [Line Items]
Debt Instrument Face Amount	325,000,000
Interest rate on Note	4.00%
5.125% senior notes due 2022 [Member]
Debt Instrument [Line Items]
Debt Instrument Face Amount	800,000,000
Interest rate on Note	5.125%
6.625% senior notes due 2042 [Member]
Debt Instrument [Line Items]
Debt Instrument Face Amount	425,000,000
Interest rate on Note	6.625%
10.0% Notes, due 2068 [Member]
Debt Instrument [Line Items]
Repurchased of 10% Debentures	2,125,000,000
Principal Amount	1,750,000,000
Interest rate on Note	10.00%
6.1% senior notes due 2041 [Member]
Debt Instrument [Line Items]
Interest rate on Note	6.10%
7.878% fixed-to-floating rate junior subordinated debentures due 2042 [Member]
Debt Instrument [Line Items]
Debt Instrument Face Amount	600,000,000
Interest rate on Note	7.878%
Proceed from Long Term Debt	586,000,000
8.125% fixed-to-floating rate junior subordinated debentures due 2068 [Member]
Debt Instrument [Line Items]
Interest rate on Note	8.125%
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
Minimum net worth required to be maintained under credit facility	0
Consolidated total debt to consolidated total capitalization ratio	0.35
Consolidated total debt of subsidiaries to consolidated total capitalization ratio	10.00%
Minimum level of consolidated net worth, Reduced	1,100,000,000
Net worth after tax	$ 14,900,000,000	$ 16,000,000,000