v3.26.3
Fair Value Measurements (Information about Valuation Techniques and Significant Unobservable Inputs Used in Valuation of Level Three Assets Measured at Fair Value on Nonrecurring Basis) (Detail)
¥ in Millions
Sep. 30, 2026
JPY (¥)
Mar. 31, 2026
JPY (¥)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Loans held for sale ¥ 60,859 ¥ 78,020
Fair Value, Measurements, Nonrecurring    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Loans held for sale 1,747 838
Real estate collateral-dependent loans (net of allowance for credit losses) 5,489 11,553
Investment in operating leases, property under facility operations and office facilities 8,517 11,907
Land and buildings undeveloped or under construction   2,203
Equity method investments 43,128 5,140
Total 68,670 74,058
Fair Value, Measurements, Nonrecurring | Level 3    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Loans held for sale 0 838
Real estate collateral-dependent loans (net of allowance for credit losses) 5,489 11,553
Investment in operating leases, property under facility operations and office facilities 8,517 11,841
Land and buildings undeveloped or under construction   2,203
Equity method investments 11,837 5,140
Total 25,843 31,575
Fair Value, Measurements, Nonrecurring | Level 3 | Direct capitalization    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Equity method investments   ¥ 844
Fair Value, Measurements, Nonrecurring | Level 3 | Direct capitalization | Capitalization rate    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Equity method investments   0.075
Fair Value, Measurements, Nonrecurring | Level 3 | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investment in operating leases, property under facility operations and office facilities   ¥ 6,283
Land and buildings undeveloped or under construction   ¥ 2,203
Fair Value, Measurements, Nonrecurring | Level 3 | Discounted cash flows | Discount rate    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Land and buildings undeveloped or under construction   0.039
Fair Value, Measurements, Nonrecurring | Level 3 | Appraisals/Broker quotes    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Loans held for sale   ¥ 838
Real estate collateral-dependent loans (net of allowance for credit losses) 5,489 11,553
Investment in operating leases, property under facility operations and office facilities 8,517 5,558
Equity method investments ¥ 11,837 1,615
Fair Value, Measurements, Nonrecurring | Level 3 | Market Multiples    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Equity method investments   ¥ 2,681
Fair Value, Measurements, Nonrecurring | Level 3 | Minimum | Discounted cash flows | Discount rate    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Investment in operating leases, property under facility operations and office facilities   0
Fair Value, Measurements, Nonrecurring | Level 3 | Minimum | Market Multiples | EV/EBITDA multiple    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Equity method investments   6.8
Fair Value, Measurements, Nonrecurring | Level 3 | Maximum | Discounted cash flows | Discount rate    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Investment in operating leases, property under facility operations and office facilities   0.053
Fair Value, Measurements, Nonrecurring | Level 3 | Maximum | Market Multiples | EV/EBITDA multiple    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Equity method investments   7.8
Fair Value, Measurements, Nonrecurring | Level 3 | Weighted Average | Direct capitalization | Capitalization rate    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Equity method investments   0.075
Fair Value, Measurements, Nonrecurring | Level 3 | Weighted Average | Discounted cash flows | Discount rate    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Investment in operating leases, property under facility operations and office facilities   0.052
Significant unobservable inputs, Land and buildings undeveloped or under construction   0.039
Fair Value, Measurements, Nonrecurring | Level 3 | Weighted Average | Market Multiples | EV/EBITDA multiple    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Equity method investments   6.9