Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Earnings Per Share [Abstract]
Shareholders' net income	$ 547		$ 534	$ 1,668	$ 1,635
Shares:
Weighted average	256,070,000		261,402,000	256,166,000	265,554,000
Common stock equivalents	4,449,000		4,489,000	4,451,000	4,507,000
Total shares	260,519,000		265,891,000	260,617,000	270,061,000
EPS, basic	$ 2.14		$ 2.04	$ 6.51	$ 6.16
EPS, effect of dilution	(0.04)		(0.03)	(0.11)	(0.11)
EPS, diluted	$ 2.10		$ 2.01	$ 6.40	$ 6.05
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Common shares held in Treasury	38,553,358		103,340,125	38,553,358	103,340,125
Shares of treasury stock retired		70,000,000
Employee Stock Option [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive options	0		0	500,000	1,300,000