Profit Per Share (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Jan. 31, 2014
Earnings Per Share [Abstract]
Common shares under SARs and stock options not included in the computation of diluted earnings per share (in shares)		8,062,177	26,168,384	8,062,177	28,919,076
Profit for the period (A) (in dollars)	[1]	$ 802	$ 550	$ 994	$ 821
Determination of shares (in millions)
Weighted-average number of common shares outstanding (B) (in shares)		590,200,000	584,100,000	588,800,000	583,400,000
Shares issuable on exercise of stock awards, net of shares assumed to be purchased out of proceeds at average market price (in shares)		5,200,000	4,500,000	5,600,000	4,800,000
Average common shares outstanding for fully diluted computation (C) (in shares)	[2]	595,400,000	588,600,000	594,400,000	588,200,000
Profit (loss) per share of common stock:
Assuming no dilution (A/B) (in dollars per share)		$ 1.36	$ 0.94	$ 1.69	$ 1.41
Assuming full dilution (A/C) (in dollars per share)	[2]	$ 1.35	$ 0.93	$ 1.67	$ 1.40
Shares outstanding as of June 30 (in shares)		591,000,000	584,200,000	591,000,000	584,200,000
Common stock repurchase
Stock repurchase program, authorized amount						$ 10,000
Common shares repurchased (in shares)				0	0
Stock repurchase program, amount of authorized repurchase spent to date				$ 4,500

[1] 1 Profit attributable to common shareholders.

[2] 2 Diluted by assumed exercise of stock-based compensation awards using the treasury stock method.