Taxes (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
U.S. federal
Current		$ (817)	$ 748	$ 15
Deferred		(580)	1,330	1,128
State and local
Current		(187)	336	120
Deferred		(109)	36	74
Total United States		(1,693)	2,450	1,337
International
Current		2,997	9,235	12,296
Deferred		(1,172)	207	675
Total International		1,825	9,442	12,971
Total income tax expense (benefit)		$ 132	$ 11,892	$ 14,308
Reconciliation between the U.S. statutory federal income tax rate and the company's effective income tax rate
U.S. statutory federal income tax rate		35.00%	35.00%	35.00%
Effect of income taxes from international operations at rates different from the U.S. statutory rate	[1]	(25.10%)	2.10%	4.40%
State and local taxes on income, net of U.S. federal income tax benefit		(1.50%)	0.70%	0.60%
Tax credits		(0.70%)	(0.20%)	(0.50%)
Other	[1],[2]	(5.00%)	0.50%	0.40%
Effective tax rate		2.70%	38.10%	39.90%

[1] 2013 and 2014 conformed to 2015 presentation.

[2] 2015 includes one-time tax benefits associated with changes in uncertain tax positions and provision-to-return adjustments.