Retirement Benefits (Details 14) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Medical and Life Benefit Plans Disclosure (Amounts in paragraphs)
Percentage current retirees participating in plans	55.00%
Expected Employer Contributions (Amounts in paragraphs)
Average future service period of employees	10 years
Other comprehensive loss changes in unamortized benefit plan costs, net of tax	$ 2,825,000,000	$ (222,000,000)	$ (584,000,000)
Defined Contribution Plans Disclosure (Amounts in paragraphs)
Defined contribution plans cost	297,000,000	288,000,000	291,000,000
Maximum percentage of employee compensation eligible for cash matching of employee contributions	4.00%
Pension Benefit Plans (Amounts in paragraphs)
Number of domestic unfunded non-qualified plans for directors, officers and certain employees	11
Accumulated benefit obligation for all defined benefit pension plans	23,600,000,000	20,500,000,000
Percentage threshold for excess gains or losses that are subject to amortization	10.00%
Information About Plan Assets (Amounts in paragraphs)
Maximum percentage of funds permitted to be invested in each trust account	no more than 5 percent
Maximum percentage of funds permitted to be invested in trusted account	5.00%
Number of real estate and private equity partnerships	162
Unfunded commitments	882,000,000	1,200,000,000
Notice period for alternative investments redemptions, days	90 days
Accumulated net after-tax actuarial losses	3,900,000,000	2,800,000,000
Tax impact due to reduction in discount rate assumption	1,200,000,000
Pension Benefits
Expected Employer Contributions (Amounts in paragraphs)
Employer contributions	1,084,000,000	789,000,000
Average future service period of employees	10 years
Other comprehensive loss changes in unamortized benefit plan costs, net of tax	2,687,000,000	(158,000,000)	(524,000,000)
Discount rate	5.03%	5.75%
Reduction in Projected benefit obligation	640,000,000
Pension Benefits | Employer Contributions - Required
Expected Employer Contributions (Amounts in paragraphs)
Expected employer contributions	65,000,000
Pension Benefits | Employer Contributions - Discretionary
Expected Employer Contributions (Amounts in paragraphs)
Expected employer contributions	0
Employer contributions	1,000,000,000	728,000,000
Medical and Life Benefits
Expected Employer Contributions (Amounts in paragraphs)
Employer contributions	111,000,000	105,000,000
Other comprehensive loss changes in unamortized benefit plan costs, net of tax	138,000,000	(64,000,000)	(60,000,000)
Medical and Life Benefits | Employer Contributions - Required
Expected Employer Contributions (Amounts in paragraphs)
Expected employer contributions	$ 120,000,000