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Life Insurance Operations - Additional Information (Detail) - JPY (¥)
¥ in Millions
12 Months Ended
Mar. 31, 2023
Mar. 31, 2022
Mar. 31, 2021
Net Investment Income [Line Items]      
Amortization of policy acquisition costs charged to income ¥ 25,966 ¥ 21,213 ¥ 21,928