Retirement Benefits - Amounts Recognized in Consolidated Income Statement (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Disclosure of net defined benefit liability (asset) [abstract]
Current service cost	¥ 30,761	¥ 30,658	¥ 32,099
Net interest cost	(3,845)	(2,843)	(1,415)
Past service cost	(4,077)	7,175	(28,023)
Total	¥ 22,839	¥ 34,990	¥ 2,661

The increase (decrease) in the net defined benefit liability (asset) resulting from employee service in the current period. [Refer: Net defined benefit liability (asset)]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- References

No definition available.

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- Definition

The increase (decrease) in the net defined benefit liability (asset) resulting from the passage of time. [Refer: Interest expense; Net defined benefit liability (asset)]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
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- Definition

The increase (decrease) in the net defined benefit liability (asset) resulting from past service cost. Past service cost is the change in the present value of the defined benefit obligation for employee service in prior periods, resulting from a plan amendment (the introduction or withdrawal of, or changes to, a defined benefit plan) or a curtailment (a significant reduction by the entity in the number of employees covered by a plan). [Refer: Net defined benefit liability (asset); Defined benefit plans [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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-IssueDate 2022-03-24
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- Definition

The amount of post-employment benefit expense included in profit or loss relating to defined benefit plans. [Refer: Profit (loss); Defined benefit plans [member]] [Contrast: Increase (decrease) in net defined benefit liability (asset) resulting from expense (income) in profit or loss]

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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