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Operating Segment Information and Concentrations of Risk - Summary of Gross Sales by Major Customers (Details) - Sales Revenue, Net - USD ($) $ in Millions | 12 Months Ended
--- | ---
Mar. 31, 2021 | Mar. 31, 2020 | Mar. 31, 2019
Geographic Concentration Risk | Non-US |  |  |
Segment Reporting Information [Line Items] |  |  |
Gross sales percentage (as percent) | 33.00% | 34.00% | 36.00%
Customer A | North America Fiber Cement | Customer Concentration Risk |  |  |
Segment Reporting Information [Line Items] |  |  |
Net sales | $ 347.3 | $ 306.0 | $ 260.5
Gross sales percentage (as percent) | 12.00% | 12.00% | 10.40%

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