Long-Duration Insurance Contracts Relating to Life Insurance Operations - Schedule of Balances of Policy Account (Detail) - Fixed Annuity And Annuitization Benefits - JPY (¥) ¥ in Millions	6 Months Ended	12 Months Ended
Sep. 30, 2023	Mar. 31, 2023
Policyholder Account Balance [Line Items]
Beginning balance	¥ 158,952	¥ 193,322
Transfer in	5,540	17,223
Surrenders and partial surrenders	(25)	(58)
Benefit payments and lump sum payments, etc	(15,142)	(50,956)
Policy charges	(113)	(262)
Transfer out	(188)	(409)
Interests	532	1,209
Others	(12)	(1,117)
Ending balance	¥ 149,544	¥ 158,952
Weighted average guaranteed interest rate (%)	0.70%	0.70%
Benefits in excess of policyholder account balances (Millions of yen)	¥ 1	¥ 1
Cash surrender value (Millions of yen)	¥ 143,335	¥ 152,578

Transfer from policyholder account balance to separate account.

No definition available.

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- Definition

Transfer to policyholder account balance from separate account.

+ References

No definition available.

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- Definition

Amount of cash to be paid to policyholder upon termination and surrender of long-duration contract issued by insurance entity.

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- Definition

Amount of interest expense for allocation to policyholder account balance.

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- Definition

Amount of cash outflow to policyholder account balance from benefit payment.

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- Definition

Amount of increase (decrease) in liability for policyholder account balance from change, classified as other.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount of guaranteed benefit in excess of current account balance of policyholder account balance.

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Amount of decrease in liability for policyholder account balance from policy charge.

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Amount of decrease in liability for policyholder account balance from contract redemption.

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- Definition

Weighted-average crediting rate for liability for policyholder account balance, calculated at a point in time.

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- Definition

Amount due to policyholder. Includes, but is not limited to, unpaid policy dividend, retrospective refund, and undistributed earnings on participating business. Excludes future policy benefit and claim expense.

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