Goodwill and other intangible assets - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Indefinite-Lived Intangible Assets [Line Items]
Impairment, Intangible Asset, Indefinite-Lived (Excluding Goodwill), Statement of Income or Comprehensive Income [Extensible Enumeration]		Other General Expense
Amortization charges associated with finite-lived intangible assets		$ 3,200	$ 2,600	$ 2,600
Total estimated amortization of finite-lived intangible assets for 2024		4,800
Total estimated amortization of finite-lived intangible assets for 2025		4,500
Total estimated amortization of finite-lived intangible assets for 2026		3,900
Total estimated amortization of finite-lived intangible assets for 2027		3,900
Total estimated amortization of finite-lived intangible assets for 2028		$ 2,900
IPR&D
Indefinite-Lived Intangible Assets [Line Items]
IPR&D impairment charge	$ 783