Fair Value Measurements (Recorded Amounts of Major Assets Measured at Fair Value on Nonrecurring Basis) (Detail) - JPY (¥) ¥ in Millions	Mar. 31, 2025	Mar. 31, 2024
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held for sale	¥ 97,694	¥ 129,959
Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held for sale		1,706
Real estate collateral-dependent loans (net of allowance for credit losses)	5,881	5,535
Investment in operating leases and property under facility operations		1,205
Investment in operating leases, property under facility operations and office facilities	8,105
Certain equity securities	15,193	18,484
Certain equity method investments	20,619	461
Total	49,798	27,391
Fair Value, Measurements, Nonrecurring \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held for sale		0
Real estate collateral-dependent loans (net of allowance for credit losses)	0	0
Investment in operating leases and property under facility operations		0
Investment in operating leases, property under facility operations and office facilities	0
Certain equity securities	0	0
Certain equity method investments	0	0
Total	0	0
Fair Value, Measurements, Nonrecurring \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held for sale		1,706
Real estate collateral-dependent loans (net of allowance for credit losses)	0	261
Investment in operating leases and property under facility operations		0
Investment in operating leases, property under facility operations and office facilities	0
Certain equity securities	15,193	18,484
Certain equity method investments	0	0
Total	15,193	20,451
Fair Value, Measurements, Nonrecurring \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held for sale		0
Real estate collateral-dependent loans (net of allowance for credit losses)	5,881	5,274
Investment in operating leases and property under facility operations		1,205
Investment in operating leases, property under facility operations and office facilities	8,105
Certain equity securities	0	0
Certain equity method investments	20,619	461
Total	¥ 34,605	¥ 6,940

Investment in operating leases and property under facility operations.

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Investment in operating leases, property under facility operations and office facilities.

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Real estate collateral-dependent loans (net allowance probable loan losses).

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Fair value portion of asset recognized for present right to economic benefit.

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Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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Fair value portion of investments in an entity not consolidated. Includes, but is not limited to, investments in an entity that is affiliated with the reporting entity by means of direct or indirect ownership, an entity in which the reporting entity shares control of the entity with another party or group, an entity which the company has significant influence, but does not have control and subsidiaries that are not required to be consolidated and are accounted for using the equity or cost method.

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Fair value portion of loans held-for-sale including, but not limited to, mortgage loans and finance receivables.

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