Commitments, Guarantees, and Contingent Liabilities - Additional Information (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
Mar. 31, 2025	Mar. 31, 2024	Mar. 31, 2023
Commitments and Contingencies Disclosure [Line Items]
Commitments for purchase of equipment to be leased at cost	¥ 11,491	¥ 8,306
Payments for computer systems under non-cancelable contracts	10,896	9,348	¥ 8,738
Estimated construction costs	143,120	131,948
Total unused credit and capital amount available	437,496	366,534
Guarantee Obligations Maximum Exposure	1,123,984	1,151,414
Guarantee Obligations Current Carrying Value	12,276	8,424
Outstanding principal amount of loans transferred under Delegated Underwriting and Servicing program	2,683,671	2,587,597
Provision for credit losses in the consolidated statements of income	5,297	440
Integrated Resort Development [Member]
Commitments and Contingencies Disclosure [Line Items]
Total unused credit and capital amount available	270,168
Other liabilities
Commitments and Contingencies Disclosure [Line Items]
Allowance for off-balance sheet credit exposure	9,766	5,116	¥ 17,843
Corporate Loans
Commitments and Contingencies Disclosure [Line Items]
Guarantee Obligations Maximum Exposure	558,862	608,543
Guarantee Obligations Current Carrying Value	5,223	4,839
Performance Guarantee \| Corporate Loans
Commitments and Contingencies Disclosure [Line Items]
Guarantee Obligations Maximum Exposure	469,000	484,000
Guarantee Obligations Current Carrying Value	¥ 2,474	¥ 2,327

Commitments and Contingencies Disclosure [Line Items]

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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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- Definition

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

+ References

No definition available.

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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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- Definition

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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Amount of expense related loan transactions, lease transactions, credit loss from transactions other than loan and lease transactions, and other loss based on assessment of uncollectability from the counterparty to reduce the account to their net realizable value.

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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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