Income Taxes Details 3 (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance as of January 1,	$ 20	$ 18	$ 24
True-up from tax return filings	0	0	(8)
Increase in unrecognized tax benefits as a result of position taken during the current period	2	2	2
Balance as of December 31,	22	20	18
Interest on income taxes expense	4
Unrecognized tax benefits that would impact effective tax rate	22
Liability under Tax Allocation Agreement	6	7
Reduction in liability for tax basis step-up adjustment	$ 1
Realization assessment period for which cumulative operating income considered	3 years