Commitments, Guarantees, and Contingent Liabilities - Additional Information (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020
Commitments and Contingencies Disclosure [Line Items]
Commitments for purchase of equipment to be leased at cost	¥ 3,475
Payments for computer systems under non-cancelable contracts	8,036	¥ 6,486	¥ 7,139
Estimated construction costs	128,449
Total unused credit and capital amount available	436,784
Guarantee Obligations Maximum Exposure	1,153,273	1,147,392
Guarantee Obligations Current Carrying Value	60,458	63,843
Outstanding principal amount of loans transferred under Delegated Underwriting and Servicing program	2,121,074	1,857,499
Provision for credit losses for off balance sheet credit exposure reversals	4,449	7,437
Other Liabilities [Member]
Commitments and Contingencies Disclosure [Line Items]
Allowance for off-balance sheet credit exposure	22,120	26,094
Corporate Loans
Commitments and Contingencies Disclosure [Line Items]
Guarantee Obligations Maximum Exposure	436,414	469,377
Guarantee Obligations Current Carrying Value	4,895	4,768
Performance Guarantee \| Corporate Loans
Commitments and Contingencies Disclosure [Line Items]
Guarantee Obligations Maximum Exposure	563,000	690,000
Guarantee Obligations Current Carrying Value	¥ 2,317	¥ 1,998

Commitments and Contingencies Disclosure [Line Items]

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Provision for credit losses for off balance sheet credit exposure reversals.

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The current carrying amount of the liability for the freestanding or embedded guarantor's obligations under the guarantee or each group of similar guarantees.

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Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions.

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The minimum amount the entity agreed to spend under the long-term purchase commitment.

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Amount of cash outflow reducing loss contingency liability.

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Reflects the estimated amount of loss from the specified contingency as of the balance sheet date.

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Amount of expected credit loss for credit exposure on off-balance-sheet commitment, including but not limited to, loan commitment, standby letter of credit, financial guarantee not accounted for as insurance. Excludes off-balance sheet credit exposure accounted for as insurance and instrument accounted for under derivatives and hedging.

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This is the principal amount outstanding for securitized loans only (across all types of loans).

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The floor amount as of the balance sheet date that the entity must expend to satisfy the terms of disclosed arrangements (excluding long-term commitments) in which the entity must commit resources to supply goods or services to one or more customers.

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