Derivative instruments (Locations and Effective Portions of Gain (Loss) Reclassified out of AOCI) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Derivative Instruments Gain Loss [Line Items]
Product sales	$ 5,474	$ 5,225	$ 10,713	$ 10,099
Interest and other income, net	137	198	287	304
Interest expense, net	(313)	(277)	(607)	(529)
Income before income taxes	2,204	1,997	4,462	3,873
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Derivative Instruments Gain Loss [Line Items]
Income before income taxes	(133)	226	33	112
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member] | Foreign currency contracts [Member]
Derivative Instruments Gain Loss [Line Items]
Product sales	79	91	175	160
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member] | Cross currency swap contracts [Member]
Derivative Instruments Gain Loss [Line Items]
Interest and other income, net	(212)	136	(142)	(47)
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member] | Forward interest rate contracts [Member]
Derivative Instruments Gain Loss [Line Items]
Interest expense, net	0	(1)	0	(1)
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member] | Cash flow hedge [Member]
Derivative Instruments Gain Loss [Line Items]
Income before income taxes	(133)	226	33	112
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member] | Cash flow hedge [Member] | Foreign currency contracts [Member]
Derivative Instruments Gain Loss [Line Items]
Product sales	79	91	175	160
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member] | Cash flow hedge [Member] | Cross currency swap contracts [Member]
Derivative Instruments Gain Loss [Line Items]
Interest and other income, net	(212)	136	(142)	(47)
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member] | Cash flow hedge [Member] | Forward interest rate contracts [Member]
Derivative Instruments Gain Loss [Line Items]
Interest expense, net	$ 0	$ (1)	$ 0	$ (1)