Long-Duration Insurance Contracts Relating to Life Insurance Operations - Schedule of Single-Payment Whole Life Insurance (Detail) - Whole Life Insurance [Member] - JPY (¥) ¥ in Millions |
6 Months Ended | 12 Months Ended |
|---|---|---|
Sep. 30, 2026 |
Mar. 31, 2026 |
|
| Liability for Future Policy Benefit, Activity [Line Items] | ||
| Beginning balance | ¥ 304,541 | ¥ 134,572 |
| New contract | 41,807 | 148,468 |
| Surrenders and partial surrenders | (10,304) | (6,555) |
| Benefit payments and lump sum payments, etc. | (675) | (950) |
| Policy charges | (1,473) | (2,107) |
| Interests | 8,120 | 11,793 |
| Effect of changes in foreign exchange rate | (4,867) | 19,320 |
| Ending balance | ¥ 337,149 | ¥ 304,541 |
| Weighted average guaranteed interest rate (%) | 5.10% | 5.50% |
| Benefits in excess of policy account balances (Millions of yen) | ¥ 0 | ¥ 0 |
| Cash surrender value (Millions of yen) | ¥ 305,965 | ¥ 292,731 |
| X | ||||||||||
- Definition Policyholder net exchange rate fluctuations. No definition available.
|
| X | ||||||||||
- Definition Amount of cash to be paid to policyholder upon termination and surrender of long-duration contract issued by insurance entity. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- Definition Amount of interest expense for allocation to policyholder account balance. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
|
| X | ||||||||||
- Definition 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. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- Definition Amount of cash outflow to policyholder account balance from benefit payment. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
|
| X | ||||||||||
- Definition Amount of increase in liability for policyholder account balance from contract issuance. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
|
| X | ||||||||||
- Definition Amount of guaranteed benefit in excess of current account balance of policyholder account balance. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- Definition Amount of decrease in liability for policyholder account balance from policy charge. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
|
| X | ||||||||||
- Definition Amount of decrease in liability for policyholder account balance from contract redemption. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
|
| X | ||||||||||
- Definition Weighted-average crediting rate for liability for policyholder account balance, calculated at a point in time. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- 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. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- Details
|