Benefit Plans (Components of net periodic cost (benefit)) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 12	$ 12	$ 13
Interest cost on projected benefit obligation	121	135	146
Expected return on plan assets	(181)	(171)	(172)
Amortization of net actuarial (gain) loss	47	39	25
Settlement loss	3
Net periodic (benefit) cost	2	15	12
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	1		1
Interest cost on projected benefit obligation	1	2	3
Amortization of prior service credit	(18)	(18)	(19)
Amortization of net actuarial (gain) loss	2	1
Net periodic (benefit) cost	$ (14)	$ (15)	$ (15)