Profit Per Share (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 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)		0	21,874,118	5,136,715	26,088,324
Profit for the period (A) (in dollars)	[1]	$ 1,059	$ 283	$ 2,053	$ 1,104
Determination of shares (in millions)
Weighted-average number of common shares outstanding (B) (in shares)		592,900,000	584,700,000	590,300,000	583,800,000
Shares issuable on exercise of stock awards, net of shares assumed to be purchased out of proceeds at average market price (in shares)		7,200,000	4,900,000	6,200,000	4,900,000
Average common shares outstanding for fully diluted computation (C) (in shares)	[2]	600,100,000	589,600,000	596,500,000	588,700,000
Profit (loss) per share of common stock:
Assuming no dilution (A/B) (in dollars per share)		$ 1.79	$ 0.48	$ 3.48	$ 1.89
Assuming full dilution (A/C) (in dollars per share)	[2]	$ 1.77	$ 0.48	$ 3.44	$ 1.88
Shares outstanding as of September 30 (in shares)		594,900,000	585,100,000	594,900,000	585,100,000
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.