Supplemental financial information - Amounts Reclassified out of AOCI (Details) - Reclassification out of Accumulated Other Comprehensive Income - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Net actuarial gains (losses) of defined benefit plans
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Reclassified from other comprehensive income (loss), before tax	[1],[2]	$ 20	$ 26	$ 40	$ 40
Tax Effect		(7)	(9)	(13)	(13)
Recognized within Net income, net of taxes		13	17	27	27
Prior service (cost) credit of defined benefit plans
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Reclassified from other comprehensive income (loss), before tax	[1],[2]	(2)	1	(3)	2
Tax Effect		1	(1)	1	(1)
Recognized within Net income, net of taxes		$ (1)	$ 0	$ (2)	$ 1

[1] Detailed in Note 7.

[2] Pension expense is included in COR, R&D and SG&A in the Consolidated Statements of Income