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Commitments and Contingencies - Additional Information (Details) - claim	12 Months Ended
	Mar. 31, 2016	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Loss Contingencies [Line Items]
Number of pending claims	426	360	393	332	336	352
New Zealand | Subsidiaries | New Zealand Weathertightness
Loss Contingencies [Line Items]
Number of claims	4
Number of pending claims	3

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.

+ References

No definition available.

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- Definition

The total number of new claims filed pertaining to a loss contingency during the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121557415&loc=d3e14435-108349

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- Definition

Number of pending claims pertaining to a loss contingency.

+ References

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-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
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