Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Earnings Per Share [Abstract]
Shareholders' net income	$ 510	$ 588	$ 1,029	$ 1,121
Shares:
Weighted average	255,381,000	255,730,000	255,101,000	256,215,000
Common stock equivalents	4,119,000	4,367,000	4,372,000	4,453,000
Total shares	259,500,000	260,097,000	259,473,000	260,668,000
EPS, basic	$ 2.00	$ 2.30	$ 4.03	$ 4.38
EPS, effect of dilution	(0.03)	(0.04)	(0.06)	(0.08)
EPS, diluted	$ 1.97	$ 2.26	$ 3.97	$ 4.30
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Common shares held in Treasury	39,587,801	38,694,585	39,587,801	38,694,585
Employee Stock Option [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive options	2,600,000	0	2,000,000	700,000