Taxes (Details 2) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Changes to company's unrecognized tax benefits
Balance at January 1	$ 3,507		$ 3,195		$ 2,696
Foreign currency effects	(2)		17		(1)
Additions based on tax positions taken in current year	469		334		459
Reductions based on tax positions taken in current year	0
Additions/reductions resulting from current-year asset acquisitions/sales	(41)
Additions for tax positions taken in prior years	236		270		533
Reductions for tax positions taken in prior years	(366)		(165)		(182)
Settlements with taxing authorities in current year	(318)		(136)		(300)
Reductions as a result of a lapse of the applicable statute of limitations	(4)		(8)		(10)
Balance at December 31	3,481		3,507		3,195
Taxes other than on income
Excise and similar taxes on products and merchandise	8,085		8,591		8,109
Total taxes other than on income	15,628	[1]	18,191	[1]	17,591	[1]
United States
Taxes other than on income
Excise and similar taxes on products and merchandise	4,199		4,484		4,573
Import duties and other levies	4				(4)
Property and other miscellaneous taxes	726		567		584
Payroll taxes	236		219		223
Taxes on production	308		271		135
Total taxes other than on income	5,473		5,541		5,511
International
Taxes other than on income
Excise and similar taxes on products and merchandise	3,886		4,107		3,536
Import duties and other levies	3,511		6,183		6,550
Property and other miscellaneous taxes	2,354		2,000		1,740
Payroll taxes	148		133		134
Taxes on production	256		227		120
Total taxes other than on income	$ 10,155		$ 12,650		$ 12,080

[1] Includes excise, value-added and similar taxes.