Stock-Based Compensation (Stock Options) (Details) (USD $) In Millions, except Share data in Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Stock Option Activity, Options [Roll Forward]
Outstanding at beginning of period	793
Granted		310	340
Exercised	(420)
Outstanding at end of period	373	793
Exercisable at end of period	53
Options expected to vest	320
Stock Option Activity, Weighted Average Exercise Price [Roll Forward]
Weighted average exercise price of options outstanding at beginning of period	$ 61
Exercised	$ 59
Weighted average exercise price of options outstanding end of period	$ 64	$ 61
Weighted average exercise price of options exercisable at end of period	$ 46
Weighted average exercise price of options expected to vest	$ 67
Weighted-Average Remaining Life [Abstract]
Weighted average remaining life of options outstanding at end of period, years	6 years 10 months 0 days
Weighted average remaining life of options exercisable at end of period, years	1 year 0 months 0 days
Weighted average remaining life of options expected to vest, years	7 years 10 months 0 days
Aggregate Intrinsic Value [Abstract]
Aggregate intrinsic value of options outstanding at end of period	$ 7
Aggregate intrinsic value of options exercisable at end of period	2
Aggregate intrinsic value of options expected to vest	5
Schedule Of Information Related To Stock Options [Abstract]
Intrinsic value of options exercised	6	26	17
Tax benefit related to options exercised	2	10	7
Cash received from options exercised	$ 25	$ 9	$ 21
Stock options granted		310	340