Long-duration insurance contracts - Summary of life, annuity and health insurance benefits liabilities (Detail) - USD ($) $ in Millions	Jun. 30, 2023	Jun. 30, 2022
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Life, annuity and health insurance benefits	$ 19,635	$ 20,952
Periodic Payment Annuities [Member]
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Life, annuity and health insurance benefits	10,820	11,826
Life and Health [Member]
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Life, annuity and health insurance benefits	5,523	5,810
Other liabilities [Member]
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Life, annuity and health insurance benefits	$ 3,292	$ 3,316