Stock-Based Compensation (Stock Options) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Stock Option Activity, Options [Roll Forward]
Outstanding at beginning of period	373
Granted			310
Exercised	(270)
Outstanding at end of period	103	373
Options expected to vest	103
Stock Option Activity, Weighted Average Exercise Price [Roll Forward]
Weighted average exercise price of options outstanding at beginning of period	$ 64
Exercised	62
Weighted average exercise price of options outstanding end of period	69	$ 64
Weighted average exercise price of options expected to vest	$ 69
Weighted-Average Remaining Life [Abstract]
Weighted average remaining life of options outstanding at end of period, years	7 years 2 months
Weighted average remaining life of options expected to vest, years	7 years 2 months
Schedule Of Information Related To Stock Options [Abstract]
Intrinsic value of options exercised	$ 5	$ 6	$ 26
Tax benefit related to options exercised	2	2	10
Cash received from options exercised	$ 17	$ 25	$ 9
Stock options granted			310