Pension Plans - Assumptions Used to Determine Pension Benefit Obligation (Detail)	12 Months Ended
Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
Defined Benefit Plan Net Periodic Benefit Cost [Abstract]
Price inflation	1.00%	1.00%	1.00%
Discount rate	0.35%	0.60%	0.70%
Interest rate on retirement savings capital	0.60%	0.60%	1.20%
Expected return on plan assets	1.75%	1.75%	1.20%
Average rate of salary increase	1.00%	1.00%	1.00%

Defined benefit plan assumptions used calculating benefit obligation price inflation.

No definition available.

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- Definition

Weighted average rate for present value of future retirement benefits cash flows, used to determine benefit obligation of defined benefit plan.

+ References

+ Details

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- Definition

Weighted average rate increase of compensation, used to determine benefit obligation of defined benefit plan. Plan includes, but is not limited to, pay-related defined benefit plan.

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+ Details

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- Definition

Weighted-average interest crediting rate used to determine benefit obligation of defined benefit plan. Plan includes, but is not limited to, cash balance and other defined benefit plans with promised interest crediting rate.

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+ Details

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- Definition

Weighted average rate of return on plan assets, reflecting average rate of earnings expected on existing plan assets and expected contributions, used to determine net periodic benefit cost of defined benefit plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (k)(3)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e2919-114920

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- References

No definition available.

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