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Operating Segment Information and Concentrations of Risk - Summary of Gross Sales by Major Customers (Detail) - Customer A [Member] - North America Fiber Cement [Member] - Sales [Member] - Customer Concentration Risk [Member] - USD ($) $ in Millions | 12 Months Ended
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Mar. 31, 2017 | Mar. 31, 2016 | Mar. 31, 2015
Segment Reporting Information [Line Items] |  |  |
Gross Sales of Major Customers | $ 226.0 | $ 197.0 | $ 177.4
Gross sales percentage | 10.30% | 10.10% | 10.70%

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