Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Earnings Per Share [Abstract]
Shareholders' net income	$ 598	$ 519
Shares:
Weighted average	255,680,000	254,822,000
Common stock equivalents	4,094,000	4,625,000
Total shares	259,774,000	259,447,000
EPS, basic	$ 2.34	$ 2.04
EPS, effect of dilution	(0.04)	(0.04)
EPS, diluted	$ 2.30	$ 2.00
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Common shares held in Treasury	39,928,289	39,638,264
Employee Stock Option [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive options	2,500,000	1,300,000