Benefit Obligations (Schedule of Net Periodic Benefit Costs Recognized) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended			9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012		Sep. 30, 2013	Sep. 30, 2012
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 9	$ 7		$ 26	$ 21
Interest cost	39	42		116	127
Expected return on plan assets	(57)	(51)	[1]	(169)	(153)	[1]
Prior service credit	0	1	[1]	1	2
Total	(9)	(1)	[1]	(26)	(3)	[1]
Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0		2	1
Interest cost	3	3		8	9
Expected return on plan assets	0	0		0	0
Prior service credit	0	0		0	0
Total	$ 3	$ 3	[1]	$ 10	$ 10	[1]

[1] As Adjusted (Note 1)