Goodwill and other intangible assets (Identifiable Intangible Assets) (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Finite-lived intangible assets:
Gross carrying amount	$ 18,847	$ 18,344
Accumulated amortization	(10,455)	(10,121)
Intangible assets, net	8,392	8,223
Indefinite-lived intangible assets:
Gross carrying amount	19,234	18,730
Accumulated amortization	(10,455)	(10,121)
Intangible assets, net	8,779	8,609
In-process Research and Development [Member]
Indefinite-lived intangible assets:
Indefinite-lived intangible assets	387	386
Developed-Product-Technology Rights [Member]
Finite-lived intangible assets:
Gross carrying amount	12,609	12,589
Accumulated amortization	(6,974)	(6,796)
Intangible assets, net	5,635	5,793
Licensing Rights [Member]
Finite-lived intangible assets:
Gross carrying amount	3,745	3,275
Accumulated amortization	(1,699)	(1,601)
Intangible assets, net	2,046	1,674
Marketing-Related Intangible Assets [Member]
Finite-lived intangible assets:
Gross carrying amount	1,316	1,319
Accumulated amortization	(948)	(920)
Intangible assets, net	368	399
R&D Technology Rights [Member]
Finite-lived intangible assets:
Gross carrying amount	1,177	1,161
Accumulated amortization	(834)	(804)
Intangible assets, net	$ 343	$ 357