Retirement Benefits (Details 1) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Pension Benefits
Components of Net Periodic Benefit Cost (Table Amounts) [Abstract]
Service cost	$ 522	$ 520	$ 531
Interest cost	1,184	1,223	1,212
Expected return on plan assets	(1,708)	(1,690)	(1,517)
Amortization of:
Prior service cost (credit)	(58)	23	35
Net loss from previous years	427	162	206
Other	7	0	0
Net periodic benefit cost	374	238	467
Medical and Life Benefits
Components of Net Periodic Benefit Cost (Table Amounts) [Abstract]
Service cost	34	32	34
Interest cost	109	114	117
Expected return on plan assets	(68)	(62)	(56)
Amortization of:
Prior service cost (credit)	(51)	(51)	(51)
Net loss from previous years	21	17	18
Other	0	(6)	0
Net periodic benefit cost	$ 45	$ 44	$ 62