Common and Preferred Stock (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Common: Par value $.25, 600,000,000 shares authorized
Outstanding - January 1	256,544,000	259,276,000	275,526,000
Issued for stock option and other benefit plans	1,110,000	2,751,000	2,284,000
Repurchase of common stock	(785,000)	(5,483,000)	(18,534,000)
Outstanding - December 31	256,869,000	256,544,000	259,276,000
Treasury stock	39,276,000	39,601,000	36,869,000
Issued - December 31	296,145,000	296,145,000	296,145,000
Common Stock, par value and shares authorized
Common stock, par value per share	$ 0.25	$ 0.25	$ 0.25
Common stock shares authorized	600,000,000	600,000,000	600,000,000
Payments For Repurchase Of Common Stock	$ 139	$ 671	$ 1,612
Shares of treasury stock retired			70,000,000
Retirement of treasury stock effect on shareholders' equity			$ 0
Preferred Stock [Abstract]
Preferred Stock, Shares Authorized	25,000,000	25,000,000	25,000,000
Preferred Stock, Par Value Per Share	$ 1	$ 1	$ 1
Preferred Stock, Shares Outstanding	0	0	0
Shareholders' Equity [Member]
Retirement of treasury stock effect on shareholders' equity			$ 0