Segment and Geographic Information - Capital Expenditures (Details) - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Mar. 31, 2026 |
Mar. 31, 2025 |
Mar. 31, 2024 |
|
| Segment Reporting Information [Line Items] | |||
| Capital expenditures incurred but not yet paid | $ 383.9 | $ 422.2 | $ 449.3 |
| Operating Segments | Siding & Trim | |||
| Segment Reporting Information [Line Items] | |||
| Capital expenditures incurred but not yet paid | 220.1 | 287.2 | 298.1 |
| Operating Segments | Deck, Rail & Accessories | |||
| Segment Reporting Information [Line Items] | |||
| Capital expenditures incurred but not yet paid | 46.7 | 0.0 | 0.0 |
| Operating Segments | Australia & New Zealand | |||
| Segment Reporting Information [Line Items] | |||
| Capital expenditures incurred but not yet paid | 60.5 | 53.1 | 47.8 |
| Operating Segments | Europe | |||
| Segment Reporting Information [Line Items] | |||
| Capital expenditures incurred but not yet paid | 46.6 | 74.3 | 89.7 |
| General Corporate and R&D | |||
| Segment Reporting Information [Line Items] | |||
| Capital expenditures incurred but not yet paid | $ 10.0 | $ 7.6 | $ 13.7 |