Pension And Other Postretirement 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	$ 11	$ 10
Interest cost	26	26
Expected return on plan assets	(34)	(31)
Amortization of prior service cost	0
Amortization of net actuarial loss	14	13
Net periodic benefit cost	17	18
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	2
Interest cost	9	9
Expected return on plan assets	(5)	(5)
Amortization of prior service cost	(1)	(1)
Amortization of net actuarial loss	5	4
Net periodic benefit cost	$ 9	$ 9