Derivative instruments and hedging activities - Schedule of information about relevant transactions outstanding (Parenthetical) (Detail) - JPY (¥)
¥ in Millions

Mar. 31, 2026

Mar. 31, 2025

Transfer of Financial Assets Accounted for as Sales [Line Items]

Gross derivative liabilities arising from the transactions at reporting dates

^[1],[2]

¥ 24,150,000

¥ 19,342,000

Interest rate contracts [Member]

Transfer of Financial Assets Accounted for as Sales [Line Items]

Gross derivative liabilities arising from the transactions at reporting dates

¥ 14,221

¥ 19,401

[1]	Includes the amount of embedded derivatives bifurcated in accordance with ASC 815.
[2]	The amounts reported include derivatives used for non-trading purposes other than those designated as formal fair value or net investment accounting hedges. These amounts have not been separately presented since such amounts were not significant as of March 31, 2025 and March 31, 2026.

- Definition

Fair value, before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

+ References + Details