Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Earnings Per Share [Abstract]
Shareholders' net income	$ 806	$ 813	$ 1,721	$ 1,411
Shares:
Weighted average	242,453	254,087	242,316	254,879
Common stock equivalents	2,886	3,974	3,248	4,034
Total shares	245,339	258,061	245,564	258,913
EPS, basic	$ 3.32	$ 3.2	$ 7.1	$ 5.54
EPS, effect of dilution	(0.03)	(0.05)	(0.09)	(0.09)
EPS, diluted	$ 3.29	$ 3.15	$ 7.01	$ 5.45
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Common shares held in Treasury	52,800	43,300	52,800	43,300
Employee Stock Option [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive options	900	1,200	900	1,900