Derivative instruments and hedging activities - Concentration of exposures to credit risk in OTC derivatives with financial institutions (Detail) - JPY (¥) ¥ in Billions	Mar. 31, 2022	Mar. 31, 2021
Derivative [Line Items]
Gross fair value of derivative assets	¥ 18,162	¥ 16,006
Financial institutions [Member]
Derivative [Line Items]
Gross fair value of derivative assets	15,667	13,474
Impact of master netting agreements	(13,193)	(11,473)
Impact of collateral	(1,669)	(1,500)
Net exposure to credit risk	¥ 805	¥ 501

Fair value, before effects of master netting arrangements, of a financial asset or other 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 assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

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Balance Type:	debit
Period Type:	instant