Taxes (Details 2) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Changes to company's unrecognized tax benefits
Balance at January 1		$ 3,031	$ 3,042	$ 3,552
Foreign currency effects		43	1
Foreign currency effects				(27)
Additions based on tax positions taken in current year		1,853	245	154
Additions for tax positions taken in prior years		1,166	181	218
Reductions for tax positions taken in prior years		(90)	(390)	(678)
Settlements with taxing authorities in current year		(1,173)	(36)	(5)
Reductions as a result of a lapse of the applicable statute of limitations		(2)	(12)	(172)
Balance at December 31		4,828	3,031	3,042
Income Tax Authority [Line Items]
Excise and similar taxes on products and merchandise		7,189	6,905	7,359
Import duties and other levies	[1]	12,331	11,668	12,030
Total taxes other than on income		12,331	11,668	12,030
United States
Income Tax Authority [Line Items]
Excise and similar taxes on products and merchandise		4,398	4,335	4,426
Import duties and other levies		11	9	4
Property and other miscellaneous taxes		1,824	1,680	1,367
Payroll taxes		241	252	270
Taxes on production		206	159	157
Total taxes other than on income		6,680	6,435	6,224
International
Income Tax Authority [Line Items]
Excise and similar taxes on products and merchandise		2,791	2,570	2,933
Import duties and other levies		45	33	40
Property and other miscellaneous taxes		2,563	2,379	2,548
Payroll taxes		137	145	161
Taxes on production		115	106	124
Total taxes other than on income		$ 5,651	$ 5,233	$ 5,806

[1] Includes excise, value-added and similar taxes. $7,189; $6,905; $7,359.