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Commitments and Contingencies - Additional Information (Detail) | Mar. 31, 2020 claim | Mar. 31, 2019 claim | Mar. 31, 2018 claim | Mar. 31, 2017 claim | Mar. 31, 2016 claim | Mar. 31, 2015 claim
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Loss Contingencies [Line Items] |  |  |  |  |  |
Loss Contingency, Pending Claims, Number | 393 | 332 | 336 | 352 | 426 | 494
New Zealand | Subsidiaries [Member] | New Zealand Weathertightness [Member] |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |
Loss Contingency, Pending Claims, Number |  |  |  |  | 4 |

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- Definition Number of pending claims pertaining to a loss contingency. + 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=82911808&loc=d3e14435-108349 + Details
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- Details
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