Retirement Benefits (Components Of Net Periodic Benefit Cost) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 104	$ 95
Interest cost	191	190
Expected return on assets	(166)	(163)
Amortization of Prior service cost	4	4
Amortization of Unrecognized net (gain) loss	61	37
Net periodic benefit cost	194	163
Retiree Medical And Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	15	15
Interest cost	38	44
Expected return on assets	(4)	(5)
Amortization of Prior service cost	(7)	(7)
Amortization of Unrecognized net (gain) loss	(2)	(2)
Net periodic benefit cost	$ 40	$ 45