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Commitments and Contingencies - Additional Information (Detail) $ in Millions | 12 Months Ended |  |  |
--- | --- | --- | --- | ---
Mar. 31, 2019 USD ($) claim | Mar. 31, 2018 USD ($) claim | Mar. 31, 2017 USD ($) claim | Mar. 31, 2016 claim | Mar. 31, 2015 claim | Mar. 31, 2014 claim
Loss Contingencies [Line Items] |  |  |  |  |  |
Loss Contingency, Pending Claims, Number | 332 | 336 | 352 | 426 | 494 | 466
Operating Leases, Rent Expense, Net | $ | $ 30.7 | $ 20.6 | $ 18.4 |  |  |
New Zealand | Subsidiaries [Member] | New Zealand Weathertightness [Member] |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |
Loss Contingency, Pending Claims, Number |  |  |  | 4 |  |

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