Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Earnings Per Share [Abstract]
Shareholders' net income	$ 915	$ 598
Shares:
Weighted average	242,179	255,680
Common stock equivalents	3,609	4,094
Total shares	245,788	259,774
EPS, basic	$ 3.78	$ 2.34
EPS, effect of dilution	(0.06)	(0.04)
EPS, diluted	$ 3.72	$ 2.3
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Common shares held in Treasury	52,900	39,900
Employee Stock Option [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive options	900	2,500