Segment information (Details 8) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information
External sales and revenues	$ 9,574	$ 9,160	$ 10,342	$ 9,461	$ 11,030	$ 10,962	$ 12,317	$ 12,702	$ 38,537	$ 47,011	$ 55,184
Net property, plant and equipment	15,322				16,090				15,322	16,090
Inside United States
Segment Reporting Information
External sales and revenues									15,956	19,218	21,122
Net property, plant and equipment	8,537				8,842				8,537	8,842
Outside the United States
Segment Reporting Information
External sales and revenues									22,581	27,793	$ 34,062
Net property, plant and equipment	$ 6,785				$ 7,248				$ 6,785	$ 7,248