Comprehensive Income (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended									3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012	Mar. 31, 2013 Pension Plans, Defined Benefit		Dec. 31, 2012 Pension Plans, Defined Benefit		Mar. 31, 2013 Equity Method Investments [Member]	Dec. 31, 2012 Equity Method Investments [Member]	Mar. 31, 2013 Pension Plans, Defined Benefit	Mar. 31, 2012 Pension Plans, Defined Benefit
Accumulated Other Comprehensive Income Loss [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Beginning Balance	$ (245)			$ (238)	[1]	$ (241)	[1]	$ (6)	$ (4)
Other Comprehensive Income Loss Before Reclassifications	(2)			0	[1]			(2)
Amounts Reclassified From Accumulated Other Comprehensive Income Loss	3			3	[1]			0
Accumulated Other Comprehensive Income (Loss), Ending Balance	(244)			(238)	[1]	(241)	[1]	(6)	(4)
Reclassifications Out of Accumulated Other Comprehensive Loss [Abstract]
Actuarial Loss	5	[2]								4	3
actuarial loss tax expense	(2)		(2)
Amounts Reclassified From Accumulated Other Comprehensive Income Loss	$ 3			$ 3	[1]			$ 0

[1] Amounts are net of tax.

[2] This accumulated other comprehensive loss component is included in the computation of net periodic pension cost (see Note 8 for additional details).