Benefit Obligations (Schedule of Net Periodic Benefit Costs Recognized) (Details) (USD $) In Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 7	$ 8	$ 14	$ 16
Interest cost	45	48	91	96
Expected return on plan assets	(51)	(50)	(101)	(100)
Recognized actuarial (gain) loss	8	2	15	4
Curtailment (gain) loss	0	(1)	(1)	(3)
Total	9	7	18	13
Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	1	1	1
Interest cost	2	3	6	7
Expected return on plan assets	0	0	0	0
Recognized actuarial (gain) loss	0	(1)	(1)	(2)
Curtailment (gain) loss	0	0	0	0
Total	$ 3	$ 3	$ 6	$ 6