Benefit Obligations (Schedule of Net Periodic Benefit Costs Recognized) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 28	$ 30	$ 29
Interest cost	182	188	193
Expected return on plan assets	(202)	(197)	(207)
Amortization of prior service cost	1	1	0
Recognized actuarial (gain) loss	29	8	1
Curtailment (gain) loss	(2)	(4)	(1)
Settlement (gain) loss	0	0	0
Special termination benefits	0	0	2
Total	36	26	17
Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	1	1
Interest cost	13	15	17
Expected return on plan assets	0	0	0
Amortization of prior service cost	0	0	0
Recognized actuarial (gain) loss	(2)	(4)	(5)
Curtailment (gain) loss	0	0	0
Settlement (gain) loss	0	0	0
Special termination benefits	0	0	0
Total	$ 12	$ 12	$ 13