Impairments and other charges (Details) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2015 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Number of Positions Eliminated, Period Percent		25.00%
Historical Exchange Rate_Venezuela	6.3
Foreign Currency Exchange Rate, Remeasurement	192
Tangible Asset Impairment Charges		$ 760	$ 47
Inventory Write-down		484	24
Severance Costs		352	28
Impairment of Intangible Assets (Excluding Goodwill)		212	10
Other Restructuring Costs		201	20
Business Exit Costs		80	0
Restructuring charges-other matters		88	0
Restructuring Charges		2,177	129	$ 0
Foreign Currency Transaction Gain (Loss), Realized	$ (199)
Total restructuring charges		2,376	$ 129
VENEZUELA
Restructuring Cost and Reserve [Line Items]
Historical Exchange Rate_Venezuela			6.3
Foreign Currency Exchange Rate, Remeasurement	192
Foreign Currency Transaction Gain (Loss), Realized	$ 199	$ 199	$ 0