Benefit Obligations (Schedule of Net Periodic Benefit Costs Recognized) (Details) (USD $) In Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 7	$ 7	$ 21	$ 23
Interest cost	45	46	136	142
Expected return on plan assets	(50)	(48)	(151)	(148)
Recognized actuarial (gain) loss	7	1	22	5
Prior service credit	1	1	1	1
Curtailment (gain) loss	0	(1)	(1)	(4)
Total	10	6	28	19
Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0	1	1
Interest cost	3	4	9	11
Expected return on plan assets	0	0	0	0
Recognized actuarial (gain) loss	(1)	(1)	(2)	(3)
Prior service credit	0	0	0	0
Curtailment (gain) loss	0	0	0	0
Total	$ 2	$ 3	$ 8	$ 9