v2.4.0.6
Share-Based Compensation (Summary of Share-Based Compensation Expense) (Details) (USD $)
In Millions, unless otherwise specified
3 Months Ended
Mar. 31, 2013
Mar. 31, 2012
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]    
Share-based compensation expense before income taxes $ 9 $ 10
Income tax benefit (4) (4)
Share-based compensation expense after income taxes $ 5 $ 6