Benefit Plans (Net Postemployment Costs) (Details) (Post-Employment [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Post-Employment [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1	$ 1	$ 1
Interest cost	1	2	1
Amortization of net loss	17	16	12
Other	(7)	121	5
Net periodic benefit costs	$ 12	$ 140	$ 19