Long-duration insurance contracts - Summary of life, annuity and health insurance benefits liabilities (Detail) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Life, annuity and health insurance benefits	$ 17,616	$ 20,213
Annuities [Member]
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Life, annuity and health insurance benefits	10,276	11,212
Life and Health [Member]
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Life, annuity and health insurance benefits	4,490	5,749
Other liabilities [Member]
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Life, annuity and health insurance benefits	$ 2,850	$ 3,252