Profit Per Share (Details) (USD $)	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014		Jan. 31, 2014	Feb. 28, 2007
Earnings Per Share [Abstract]
Profit for the period (A) (in dollars)	$ 1,111,000,000	[1]	$ 922,000,000	[1]
Determination of shares (in millions)
Weighted-average number of common shares outstanding (B) (in shares)	604,900,000		626,700,000
Shares issuable on exercise of stock awards, net of shares assumed to be purchased out of proceeds at average market price (in shares)	7,800,000		12,600,000
Average common shares outstanding for fully diluted computation (C) (in shares)	612,700,000	[2]	639,300,000	[2]
Profit (loss) per share of common stock:
Assuming no dilution (A/B) (in dollars per share)	$ 1.84		$ 1.47
Assuming full dilution (A/C) (in dollars per share)	$ 1.81	[2]	$ 1.44	[2]
Shares outstanding as of March 31 (in millions)	603,600,000		624,200,000
Common shares under SARs and stock options not included in the computation of diluted earnings per share (in shares)	22,360,627		10,415,733
Common stock repurchase
Stock repurchase program, authorized amount					10,000,000,000	7,500,000,000
Common shares repurchased (in shares)	4,779,963		18,110,735
Payments for repurchase of common stock	400,000,000		1,738,000,000
Stock repurchase program, amount of authorized repurchase spent to date	$ 2,900,000,000

[1] 1 Profit attributable to common stockholders.

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