Benefit Plans (Components of net periodic cost (benefit)) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Defined Benefit Plan Disclosure [Line Items]
Curtailment gain			$ 86
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	3	3	7	9
Interest cost on projected benefit obligation	33	30	99	90
Expected return on plan assets	(48)	(45)	(144)	(135)
Amortization of net actuarial (gain) loss	6	10	19	34
Settlement loss		3		3
Net periodic cost (benefit)	(6)	1	(19)	1
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost on projected benefit obligation			1	1
Amortization of prior service credit		(4)	(9)	(13)
Amortization of net actuarial (gain) loss		1		1
Curtailment gain			86
Net periodic cost (benefit)		$ (3)	$ (94)	$ (11)