Acquisitions and divestitures - ChemoCentryx Inc. Narrative (Details) - USD ($) $ / shares in Units, $ in Millions		12 Months Ended
	Oct. 20, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Business Acquisition [Line Items]
Goodwill		$ 18,629	$ 15,529	$ 14,890
ChemoCentryx, Inc.
Business Acquisition [Line Items]
Acquisition price per share (in usd per share)	$ 52.00
Total consideration	$ 3,900
Goodwill, net decrease		$ 18
Cash purchase price	3,700
Business acquisition, cash consideration paid to equity holders for pre-acquisition services	181
Inventories	$ 41
Business combination, turnover period of inventory acquired	13 months
Deferred tax liability, net	$ (502)
Goodwill	649
ChemoCentryx, Inc. | Developed-product-technology rights
Business Acquisition [Line Items]
Finite-lived intangible assets	$ 3,499
Weighted average period of amortization	11 years