Profit Per Share (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012
Earnings Per Share [Abstract]
Profit for the period (A) (in millions of dollars)	$ 880	[1]	$ 1,586	[1]
Weighted-average common shares outstanding:
Weighted-average number of common shares outstanding (B) (in shares)	656,200,000		650,000,000
Shares issuable on exercise of stock awards, net of shares assumed to be purchased out of proceeds at average market price (in shares)	15,400,000		20,200,000
Average common shares outstanding for fully diluted computation (C) (in shares)	671,600,000	[2]	670,200,000	[2]
Profit (loss) per share of common stock:
Assuming no dilution (A/B) (in dollars per share)	$ 1.34		$ 2.44
Assuming full dilution (A/C) (in dollars per share)	$ 1.31	[2]	$ 2.37	[2]
Shares outstanding as of March 31	657,500,000		652,300,000
Common shares under SARs and stock options not included in the computation of diluted earnings per share (in shares)	10,312,876		3,458,845

[1] 1 Profit attributable to common stockholders.

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