Supplemental financial information - Details on amounts reclassified out of AOCI recognized within Net income (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013		Jun. 30, 2014		Jun. 30, 2013
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest and debt expense	$ 24		$ 24		$ 49		$ 47
Tax effect	278		222		462		234
Net income	(683)		(660)		(1,170)		(1,022)
Reclassification out of Accumulated Other Comprehensive Income | Net actuarial gains (losses) of defined benefit plans
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Recognized net actuarial loss and Settlement losses	18	[1],[2]	21	[1],[2]	33	[1],[2]	47	[1],[2]
Tax effect	(7)		(5)		(12)		(14)
Net income	11		16		21		33
Reclassification out of Accumulated Other Comprehensive Income | Prior service cost of defined benefit plans
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization of prior service cost (credit) and Curtailment gain	1	[1],[2]	(3)	[1],[2]	1	[1],[2]	(3)	[1],[2]
Tax effect	0		1		0		1
Net income	1		(2)		1		(2)
Reclassification out of Accumulated Other Comprehensive Income | Derivative instruments
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest and debt expense	1		0		1		1
Tax effect	0		0		0		0
Net income	$ 1		$ 0		$ 1		$ 1

[1] Detailed in Note 7.

[2] Pension expense 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.