Goodwill and other intangible assets (Identifiable Intangible Assets) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Gross carrying amounts	$ 31,979	$ 31,991
Accumulated amortization	(14,755)	(12,632)
Other intangible assets, net	17,224	19,359
Gross carrying amount	32,009	32,045
Accumulated amortization	(14,755)	(12,632)
Intangible assets, net	17,254	19,413
In-process Research and Development [Member]
Indefinite-lived Intangible Assets [Line Items]
Indefinite-lived intangible assets	30	54
Developed-Product-Technology Rights [Member]
Finite-Lived Intangible Assets [Line Items]
Gross carrying amounts	25,572	25,575
Accumulated amortization	(9,998)	(8,322)
Other intangible assets, net	15,574	17,253
Licensing Rights [Member]
Finite-Lived Intangible Assets [Line Items]
Gross carrying amounts	3,747	3,761
Accumulated amortization	(2,710)	(2,398)
Other intangible assets, net	1,037	1,363
Marketing-Related Rights [Member]
Finite-Lived Intangible Assets [Line Items]
Gross carrying amounts	1,365	1,382
Accumulated amortization	(1,019)	(965)
Other intangible assets, net	346	417
Research and Development Technology Rights [Member]
Finite-Lived Intangible Assets [Line Items]
Gross carrying amounts	1,295	1,273
Accumulated amortization	(1,028)	(947)
Other intangible assets, net	$ 267	$ 326