Annual and transition report of foreign private issuers pursuant to Section 13 or 15(d)

Revenues - Disaggregation of Revenue (Details)

v3.21.1
Revenues - Disaggregation of Revenue (Details) - USD ($)
$ in Millions
 12 Months Ended
Mar. 31, 2021
Mar. 31, 2020
Mar. 31, 2019
Disaggregation of Revenue [Line Items]      
Net sales $ 2,908.7 $ 2,606.8 $ 2,506.6
Fiber cement revenues      
Disaggregation of Revenue [Line Items]      
Net sales 2,553.7 2,282.8 2,159.5
Fiber gypsum revenues      
Disaggregation of Revenue [Line Items]      
Net sales 355.0 323.4 332.5
Other revenues      
Disaggregation of Revenue [Line Items]      
Net sales   0.6 14.6
North America Fiber Cement      
Disaggregation of Revenue [Line Items]      
Net sales 2,040.2 1,816.4 1,676.9
North America Fiber Cement | Fiber cement revenues      
Disaggregation of Revenue [Line Items]      
Net sales 2,040.2 1,816.4 1,676.9
North America Fiber Cement | Fiber gypsum revenues      
Disaggregation of Revenue [Line Items]      
Net sales 0.0 0.0 0.0
North America Fiber Cement | Other revenues      
Disaggregation of Revenue [Line Items]      
Net sales   0.0 0.0
Asia Pacific Fiber Cement      
Disaggregation of Revenue [Line Items]      
Net sales 458.2 418.4 446.8
Asia Pacific Fiber Cement | Fiber cement revenues      
Disaggregation of Revenue [Line Items]      
Net sales 458.2 418.4 446.8
Asia Pacific Fiber Cement | Fiber gypsum revenues      
Disaggregation of Revenue [Line Items]      
Net sales 0.0 0.0 0.0
Asia Pacific Fiber Cement | Other revenues      
Disaggregation of Revenue [Line Items]      
Net sales   0.0 0.0
Europe Building Products      
Disaggregation of Revenue [Line Items]      
Net sales 410.3 371.4 368.3
Europe Building Products | Fiber cement revenues      
Disaggregation of Revenue [Line Items]      
Net sales 55.3 48.0 35.8
Europe Building Products | Fiber gypsum revenues      
Disaggregation of Revenue [Line Items]      
Net sales 355.0 323.4 332.5
Europe Building Products | Other revenues      
Disaggregation of Revenue [Line Items]      
Net sales   0.0 0.0
Other Businesses      
Disaggregation of Revenue [Line Items]      
Net sales $ 0.0 0.6 14.6
Other Businesses | Fiber cement revenues      
Disaggregation of Revenue [Line Items]      
Net sales   0.0 0.0
Other Businesses | Fiber gypsum revenues      
Disaggregation of Revenue [Line Items]      
Net sales   0.0 0.0
Other Businesses | Other revenues      
Disaggregation of Revenue [Line Items]      
Net sales   $ 0.6 $ 14.6