Supplemental financial information - Details on amounts reclassified out of AOCI recognized within Net income (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest and debt expense	$ 23		$ 24		$ 72		$ 71
Tax effect	329		187		791		421
Net income	(826)		(629)		(1,996)		(1,651)
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	25	[1],[2]	24	[1],[2]	58	[1],[2]	71	[1],[2]
Tax effect	(8)		(11)		(20)		(25)
Net income	17		13		38		46
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]	(2)	[1],[2]	0	[1],[2]	(5)	[1],[2]
Tax effect	0		1		0		2
Net income	(1)		(1)		0		(3)
Reclassification out of Accumulated Other Comprehensive Income | Derivative instruments
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest and debt expense	0		0		1		2
Tax effect	0		0		0		(1)
Net income	$ 0		$ 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.