Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Earnings Per Share [Abstract]
Shareholders' net income	$ 560	$ 456	$ 1,971	$ 1,485
Shares:
Weighted average	249,242,000	255,519,000	252,980,000	255,242,000
Common stock equivalents	4,168,000	4,235,000	4,078,000	4,326,000
Total shares	253,410,000	259,754,000	257,058,000	259,568,000
EPS, basic	$ 2.25	$ 1.78	$ 7.79	$ 5.82
EPS, effect of dilution	(0.04)	(0.02)	(0.12)	(0.1)
EPS, diluted	$ 2.21	$ 1.76	$ 7.67	$ 5.72
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Common shares held in Treasury	48,572,794	39,425,208	48,572,794	39,425,208
Employee Stock Option [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive options	0	2,600,000	1,200,000	2,200,000