Equity, Share Activity Rollforward (Details) - shares	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Share Activity
Treasury stock, shares, beginning balance	(222,000,024)
Treasury stock, shares, ending balance	(235,534,764)
Common Stock [Member]
Share Activity
Common stock, shares, beginning balance	673,000,000	673,000,000
Stock issuances, shares	0	0
Common stock, shares, ending balance	673,000,000	673,000,000
Treasury Stock [Member]
Share Activity
Treasury stock, shares, beginning balance	(222,000,000)	(200,000,000)
Stock issuances, shares	0	1,000,000
Treasury stock, shares, ending balance	(236,000,000)	(220,000,000)
Treasury Stock [Member] | Stock-Based Compensation Plans Purchase Program [Member]
Share Activity
Stock purchases, shares	0	(1,000,000)
Treasury Stock [Member] | Common Stock Purchase Program [Member]
Share Activity
Stock purchases, shares	(14,000,000)	(20,000,000)