Stock-Based Compensation Schedule of Non-qualified Stock Option Activity (Details) (USD $) In Millions, except Share data, unless otherwise specified	6 Months Ended	12 Months Ended
	Jun. 30, 2012	Dec. 31, 2011
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Options, Outstanding	18,276,862	17,665,902
Options, Outstanding, Weighted Average Exercise Price	$ 17.24	$ 17.32
Options, Outstanding, Weighted Average Remaining Contractual Term	4 years 6 months	4 years 9 months 18 days
Options, Outstanding, Intrinsic Value	$ 28	$ 26
Options, Grants in Period, Gross	888,407
Options, Grants in Period, Weighted Average Exercise Price	$ 15.33
Options, Exercises in Period	159,700
Options, Exercises in Period, Weighted Average Exercise Price	$ 16.07
Options, Forfeitures in Period	43,447
Options, Forfeitures in Period, Weighted Average Exercise Price	$ 11.76
Options, Expirations in Period	74,300
Options, Expirations in Period, Weighted Average Exercise Price	$ 17.74
Options, Exercisable	8,835,451
Options, Exercisable, Weighted Average Exercise Price	$ 18.69
Options, Exercisable, Weighted Average Remaining Contractual Term	4 years 3 months 18 days
Options, Exercisable, Intrinsic Value	7
Options, Vested and Expected to Vest, Outstanding	17,866,052
Options, Vested and Expected to Vest, Outstanding, Weighted Average Exercise Price	$ 17.31
Options, Vested and Expected to Vest, Outstanding, Weighted Average Remaining Contractual Term	4 years 4 months 24 days
Options, Vested and Expected to Vest, Outstanding, Aggregate Intrinsic Value	$ 27