Shareholders' Equity (Details) - USD ($)	1 Months Ended	3 Months Ended		9 Months Ended		66 Months Ended
	Oct. 31, 2017	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Feb. 28, 2017	Nov. 30, 2014	Apr. 30, 2012
Common Stock Programs
Shares purchased (in shares)						104,700,000
Total cost of shares purchased				$ 1,913,000,000		$ 9,100,000,000
Treasury stock acquired, additional transaction costs		$ 3,800,000		$ 9,500,000
Weighted average shares outstanding
Shares for basic earnings per share (in shares)		255,600,000	267,500,000	260,900,000	269,100,000
Dilutive effect of potentially issuable shares (in shares)		1,700,000	2,100,000	2,000,000	1,900,000
Shares for diluted earnings per share (in shares)		257,300,000	269,600,000	262,900,000	271,000,000
Number of shares excluded from the calculation of diluted earnings per share (in shares)		0	0	0	0
Share Repurchase Program of 2014
Common Stock Programs
Share repurchase authorization limit (up to)		$ 15,000,000,000.0		$ 15,000,000,000.0		15,000,000,000.0	$ 5,000,000,000.0	$ 5,000,000,000.0
Share repurchase, remaining authorization limit (in shares)		$ 5,900,000,000		$ 5,900,000,000		$ 5,900,000,000
2012 - Share Repurchase Program
Common Stock Programs
Share repurchase authorization limit (up to)									$ 5,000,000,000.0
Shares purchased (in shares)		5,400,000	2,700,000	14,500,000	10,400,000
Average price per share of stock repurchased (in dollars per share)		$ 139.61	$ 110.26	$ 131.58	$ 101.16
Total cost of shares purchased		$ 749,000,000	$ 301,000,000	$ 1,900,000,000	$ 1,100,000,000
Subsequent Event | 2012 - Share Repurchase Program
Common Stock Programs
Shares purchased (in shares)	165,000
Average price per share of stock repurchased (in dollars per share)	$ 146.52
Total cost of shares purchased	$ 24,200,000