v3.26.1
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
 12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Mar. 31, 2024
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] ¥ 0 [3]
Interest rate swap agreements | Interest expense      
Derivative Instruments, Gain (Loss) [Line Items]      
Gains (losses) recognized in income on derivative [4] 0 0 4
Interest rate swap agreements | Other (income) and expense      
Derivative Instruments, Gain (Loss) [Line Items]      
Gains (losses) recognized in income on derivative 17 39 92
Futures | Life insurance premiums and related investment income      
Derivative Instruments, Gain (Loss) [Line Items]      
Gains (losses) recognized in income on derivative (1,433) [1] (262) [2] (3,046) [3]
Futures | Interest expense      
Derivative Instruments, Gain (Loss) [Line Items]      
Gains (losses) recognized in income on derivative [4] 0 0 0
Futures | Other (income) and expense      
Derivative Instruments, Gain (Loss) [Line Items]      
Gains (losses) recognized in income on derivative 2,784 300 1,073
Foreign exchange contracts | Life insurance premiums and related investment income      
Derivative Instruments, Gain (Loss) [Line Items]      
Gains (losses) recognized in income on derivative (30,694) [1] (10,355) [2] 40,127 [3]
Foreign exchange contracts | Interest expense      
Derivative Instruments, Gain (Loss) [Line Items]      
Gains (losses) recognized in income on derivative [4] (6,679) (22,260) 2,980
Foreign exchange contracts | Other (income) and expense      
Derivative Instruments, Gain (Loss) [Line Items]      
Gains (losses) recognized in income on derivative (6,308) (1,910) 16,152
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] 0 [3]
Credit derivatives held/written | Interest expense      
Derivative Instruments, Gain (Loss) [Line Items]      
Gains (losses) recognized in income on derivative [4] 0 0 0
Credit derivatives held/written | Other (income) and expense      
Derivative Instruments, Gain (Loss) [Line Items]      
Gains (losses) recognized in income on derivative 16 0 (27)
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] 0 [3]
Options held/written and other | Interest expense      
Derivative Instruments, Gain (Loss) [Line Items]      
Gains (losses) recognized in income on derivative [4] 0 0 0
Options held/written and other | Other (income) and expense      
Derivative Instruments, Gain (Loss) [Line Items]      
Gains (losses) recognized in income on derivative ¥ (1,630) ¥ (7,399) ¥ 750
[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 fiscal 2026 (see Note 23 “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 fiscal 2025 (see Note 23 “Income and Expenses Relating to Life Insurance Operations”).
[3] 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 fiscal 2024 (see Note 23 “Income and Expenses Relating to Life Insurance Operations”).
[4] 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.