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Pension Plans - Additional Information (Detail) - JPY (¥) ¥ in Millions | 12 Months Ended
--- | ---
Mar. 31, 2025 | Mar. 31, 2024 | Mar. 31, 2023
Japan |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Accumulated benefit obligations for all defined benefit pension plans | ¥ 85,077 | ¥ 95,069 |
Expected pension plans contribution by Company and certain subsidiaries in 2025 | 3,843 |  |
Cost recognized for defined contribution pension plans of Company and certain of its subsidiaries | ¥ 2,118 | ¥ 2,146 | ¥ 2,100
Japan | Equity securities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Portfolio of plans | 30.00% | 30.00% |
Japan | Debt Securities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Portfolio of plans | 40.00% | 40.00% |
Japan | Other assets |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Portfolio of plans | 30.00% | 30.00% |
Overseas plans |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Accumulated benefit obligations for all defined benefit pension plans | ¥ 117,478 | ¥ 123,600 |
Other Foreign Benefit Plans |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Expected pension plans contribution by Company and certain subsidiaries in 2025 | 2,305 |  |
Cost recognized for defined contribution pension plans of Company and certain of its subsidiaries | ¥ 5,046 | ¥ 4,219 | ¥ 3,498
Other Foreign Benefit Plans | Equity securities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Portfolio of plans | 40.00% | 40.00% |
Other Foreign Benefit Plans | Debt Securities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Portfolio of plans | 60.00% | 50.00% |
Other Foreign Benefit Plans | Other assets |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Portfolio of plans |  | 10.00% |

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- Definition Amount of actuarial present value of benefits attributed to employee service rendered, excluding assumptions about future compensation level. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (e) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480506/715-20-50-1 + Details
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- Definition Amount of contribution expected to be received by defined benefit plan from employer in next fiscal year following current fiscal year. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 18 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480482/715-20-55-18 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (g) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480506/715-20-50-1 + Details
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- Definition Percentage of actual investment allocation to total plan assets. Includes, but is not limited to, percentage on weighted-average basis if more than one plan. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (d)(i) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480506/715-20-50-1 + Details
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