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	$ 21	$ 20
Interest cost	43	45
Expected return on plan assets	(54)	(54)
Amortization of prior service cost (benefit)
Amortization of actuarial loss	20	11
Net periodic benefit cost	30	22
Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	6	6
Interest cost	14	15
Expected return on plan assets	(14)	(14)
Amortization of prior service cost (benefit)	(1)	(2)
Amortization of actuarial loss	4	1
Net periodic benefit cost	$ 9	$ 6