Supplemental financial information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2013		Jun. 30, 2012		Jun. 30, 2013		Jun. 30, 2012
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Derivative instruments	$ (24)		$ (20)		$ (47)		$ (41)
Taxes	(222)		(130)		(234)		(226)
Net income	660		446		1,022		711
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Defined Benefit Plans Adjustment, Net Unamortized Gain (Loss) [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Net actuarial gains (losses) of defined benefit plans	21	[1],[2]	18	[1],[2]	47	[1],[2]	37	[1],[2]
Taxes	(5)		(6)		(14)		(14)
Net income	16		12		33		23
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Defined Benefit Plans Adjustment, Net Prior Service Cost (Credit) [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Prior service cost of defined benefit plans	(3)	[2],[3]	0	[2],[3]	(3)	[2],[3]	(1)	[2],[3]
Taxes	1		0		1		1
Net income	(2)		0		(2)		0
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Other Derivative Contract [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Derivative instruments	0		0		1		0
Taxes	0		0		0		0
Net income	$ 0		$ 0		$ 1		$ 0

[1] Net actuarial gains (losses) of defined benefit plans is equal to the sum of Recognized net actuarial loss and Settlement loss as detailed in Note 7.

[2] This AOCI component is included in the computation of total employee benefit cost which is allocated to COR, R&D, SG&A and Restructuring charges/other in the Consolidated statements of income.

[3] Prior service cost of defined benefit plans is equal to the sum of Amortization of prior service cost (credit) and Curtailment gain as detailed in Note 7.