Employee Benefit Plans (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	$ 25	$ 21
Interest cost	46	44
Expected return on plan assets	(35)	(34)
Amortization of unrecognized gain and prior service cost	5	(5)
Net periodic benefit costs	41	26
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	13	12
Interest cost	31	31
Expected return on plan assets	(1)	(1)
Amortization of unrecognized gain and prior service cost	(1)
Net periodic benefit costs	$ 42	$ 42