Significant Concentrations of Credit Risk - Additional Information (Detail) - JPY (¥) ¥ in Billions	12 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Concentration Risk [Line Items]
Concentration of risk description	no concentration with a single obligor exceeded 1% of the Company’s consolidated total assets.	no concentration with a single obligor exceeded 1% of the Company’s consolidated total assets.
Transportation equipment \| Assets
Concentration Risk [Line Items]
Concentration risk , percentage	10.00%	11.40%
Consumer - Real Estate Loans \| Assets
Concentration Risk [Line Items]
Concentration risk , percentage	14.40%	13.10%
Japan \| Geographic Concentration Risk \| Assets
Concentration Risk [Line Items]
Credit exposures on a geographic basis	¥ 6,995	¥ 6,363
Concentration risk , percentage	73.00%	72.00%
United States \| Geographic Concentration Risk \| Assets
Concentration Risk [Line Items]
Credit exposures on a geographic basis	¥ 1,374	¥ 1,075

Maximum amount of loss due to credit risk that, based on the gross fair value of the financial instrument, the entity would incur if parties to the financial instruments that make up the concentration failed completely to perform according to the terms of the contracts and the collateral or other security, if any, for the amount due proved to be of no value to the entity.

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-Name Accounting Standards Codification
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- Definition

Description of risks that arise due to the nature or amount of financing received from a particular lender or reliance placed on that lender. At a minimum, the description informs financial statement users of the general nature of the risk.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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