v3.26.3
Derivative Financial Instruments and Hedging (Effect of Derivative Instruments on Consolidated Statements of Income, Pre-tax, Derivatives not designated as hedging instruments) (Detail) - Nondesignated - JPY (¥)
¥ in Millions
 6 Months Ended
Sep. 30, 2026
Sep. 30, 2025
Interest rate swap agreements | Life insurance premiums and related investment income    
Derivative Instruments, Gain (Loss) [Line Items]    
Gains (losses) recognized in income on derivative ¥ 0 [1] ¥ 0 [2]
Interest rate swap agreements | Interest expense    
Derivative Instruments, Gain (Loss) [Line Items]    
Gains (losses) recognized in income on derivative [3] 0 0
Interest rate swap agreements | Services income    
Derivative Instruments, Gain (Loss) [Line Items]    
Gains (losses) recognized in income on derivative 0  
Interest rate swap agreements | Services expenses    
Derivative Instruments, Gain (Loss) [Line Items]    
Gains (losses) recognized in income on derivative 0  
Interest rate swap agreements | Other (income) and expense    
Derivative Instruments, Gain (Loss) [Line Items]    
Gains (losses) recognized in income on derivative 15 33
Futures | Life insurance premiums and related investment income    
Derivative Instruments, Gain (Loss) [Line Items]    
Gains (losses) recognized in income on derivative (292) [1] (1,106) [2]
Futures | Interest expense    
Derivative Instruments, Gain (Loss) [Line Items]    
Gains (losses) recognized in income on derivative [3] 0 0
Futures | Services income    
Derivative Instruments, Gain (Loss) [Line Items]    
Gains (losses) recognized in income on derivative (2)  
Futures | Services expenses    
Derivative Instruments, Gain (Loss) [Line Items]    
Gains (losses) recognized in income on derivative 15  
Futures | Other (income) and expense    
Derivative Instruments, Gain (Loss) [Line Items]    
Gains (losses) recognized in income on derivative 1,946 2,513
Foreign exchange contracts | Life insurance premiums and related investment income    
Derivative Instruments, Gain (Loss) [Line Items]    
Gains (losses) recognized in income on derivative (386) [1] (3,070) [2]
Foreign exchange contracts | Interest expense    
Derivative Instruments, Gain (Loss) [Line Items]    
Gains (losses) recognized in income on derivative [3] (2,950) (2,436)
Foreign exchange contracts | Services income    
Derivative Instruments, Gain (Loss) [Line Items]    
Gains (losses) recognized in income on derivative 0  
Foreign exchange contracts | Services expenses    
Derivative Instruments, Gain (Loss) [Line Items]    
Gains (losses) recognized in income on derivative 0  
Foreign exchange contracts | Other (income) and expense    
Derivative Instruments, Gain (Loss) [Line Items]    
Gains (losses) recognized in income on derivative 2,518 (11,733)
Credit derivatives held/written | Life insurance premiums and related investment income    
Derivative Instruments, Gain (Loss) [Line Items]    
Gains (losses) recognized in income on derivative 0 [1] 0 [2]
Credit derivatives held/written | Interest expense    
Derivative Instruments, Gain (Loss) [Line Items]    
Gains (losses) recognized in income on derivative [3] 0 0
Credit derivatives held/written | Services income    
Derivative Instruments, Gain (Loss) [Line Items]    
Gains (losses) recognized in income on derivative 0  
Credit derivatives held/written | Services expenses    
Derivative Instruments, Gain (Loss) [Line Items]    
Gains (losses) recognized in income on derivative 0  
Credit derivatives held/written | Other (income) and expense    
Derivative Instruments, Gain (Loss) [Line Items]    
Gains (losses) recognized in income on derivative (2) (2)
Options held/written and other | Life insurance premiums and related investment income    
Derivative Instruments, Gain (Loss) [Line Items]    
Gains (losses) recognized in income on derivative 0 [1] 0 [2]
Options held/written and other | Interest expense    
Derivative Instruments, Gain (Loss) [Line Items]    
Gains (losses) recognized in income on derivative [3] 0 0
Options held/written and other | Services income    
Derivative Instruments, Gain (Loss) [Line Items]    
Gains (losses) recognized in income on derivative 0  
Options held/written and other | Services expenses    
Derivative Instruments, Gain (Loss) [Line Items]    
Gains (losses) recognized in income on derivative 0  
Options held/written and other | Other (income) and expense    
Derivative Instruments, Gain (Loss) [Line Items]    
Gains (losses) recognized in income on derivative ¥ (2,474) ¥ 95
[1] Futures and foreign exchange contracts in the above table include gains (losses) arising from futures and foreign exchange contracts held to economically hedge the minimum guarantee risk of variable annuity and variable life insurance contracts for the six months ended September 30, 2026 (see Note 17 “Income and Expenses Relating to Life Insurance Operations”).
[2] Futures and foreign exchange contracts in the above table include gains (losses) arising from futures and foreign exchange contracts held to economically hedge the minimum guarantee risk of variable annuity and variable life insurance contracts for the six months ended September 30, 2025 (see Note 17 “Income and Expenses Relating to Life Insurance Operations”).
[3] The portion of gains (losses) recognized in income on derivative arising from foreign exchange contracts that represents interest rate adjustments is recognized as interest expense.