Accounting for Stock-Based Compensation (Schedule of Share-based Compensation, Stock Options, Activity) (Details) (Employee Stock Option [Member], USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2014
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning Balance, shares	3,737,545
Exercised, Shares	(174,462)
Forfeited and Cancelled, Shares	(7,672)
Ending Balance, shares	3,555,411
Beginning of Period, Weighted Average Exercise Price	$ 34.88
Exercised, Weighted Average Exercise Price	$ 35.01
Forfeited and Cancelled, Weighted Average Exercise Price	$ 34.61
End of Period, Weighted Average Exercise Price	$ 34.87
Weighted Average Remaining Contractual Term	3 years 10 months 24 days
Aggregate Intrinsic Value	$ 17
Exercisable, Shares	3,426,809
Exercisable, Weighted Average Exercise Price	$ 35.40
Exercisable, Weighted Average Remaining Contractual Term	3 years 8 months 12 days
Exercisable, Aggregate Intrinsic Value	$ 14