Retirement Benefits (Details) (Unaudited) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Amortization of:
Defined contribution plans cost	$ 76	$ 85
Pension Benefits
Components of Net Periodic Benefit Cost
Service cost	131	130
Interest cost	296	305
Expected return on plan assets	(427)	(423)
Amortization of:
Prior service cost (credit)	(15)	6
Net loss from previous years	107	41
Other	2	0
Net periodic benefit cost	94	59
Employer Contributions
Employer contributions required	65
Employer contributions	17
Medical and Life Benefits
Components of Net Periodic Benefit Cost
Service cost	8	8
Interest cost	27	29
Expected return on plan assets	(17)	(16)
Amortization of:
Prior service cost (credit)	(12)	(13)
Net loss from previous years	5	3
Other	0	0
Net periodic benefit cost	11	11
Employer Contributions
Employer contributions required	120
Employer contributions	$ 14