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

Revenues (Details)

v3.20.1
Revenues (Details) - USD ($)
$ in Millions
 12 Months Ended
Mar. 31, 2020
Mar. 31, 2019
Mar. 31, 2018
Segment Reporting, Revenue Reconciling Item [Line Items]      
Net sales $ 2,606.8 $ 2,506.6 $ 2,054.5
Fiber cement revenues      
Segment Reporting, Revenue Reconciling Item [Line Items]      
Net sales 2,282.8 2,159.5 2,039.8
Fiber gypsum revenues      
Segment Reporting, Revenue Reconciling Item [Line Items]      
Net sales 323.4 332.5 0.0
Other revenues      
Segment Reporting, Revenue Reconciling Item [Line Items]      
Net sales 0.6 14.6 14.7
North America Fiber Cement      
Segment Reporting, Revenue Reconciling Item [Line Items]      
Net sales 1,816.4 1,676.9 1,578.1
North America Fiber Cement | Fiber cement revenues      
Segment Reporting, Revenue Reconciling Item [Line Items]      
Net sales 1,816.4 1,676.9 1,578.1
North America Fiber Cement | Fiber gypsum revenues      
Segment Reporting, Revenue Reconciling Item [Line Items]      
Net sales 0.0 0.0 0.0
North America Fiber Cement | Other revenues      
Segment Reporting, Revenue Reconciling Item [Line Items]      
Net sales 0.0 0.0 0.0
Asia Pacific Fiber Cement      
Segment Reporting, Revenue Reconciling Item [Line Items]      
Net sales 418.4 446.8 425.4
Asia Pacific Fiber Cement | Fiber cement revenues      
Segment Reporting, Revenue Reconciling Item [Line Items]      
Net sales 418.4 446.8 425.4
Asia Pacific Fiber Cement | Fiber gypsum revenues      
Segment Reporting, Revenue Reconciling Item [Line Items]      
Net sales 0.0 0.0 0.0
Asia Pacific Fiber Cement | Other revenues      
Segment Reporting, Revenue Reconciling Item [Line Items]      
Net sales 0.0 0.0 0.0
Europe Building Products      
Segment Reporting, Revenue Reconciling Item [Line Items]      
Net sales 371.4 368.3 36.3
Europe Building Products | Fiber cement revenues      
Segment Reporting, Revenue Reconciling Item [Line Items]      
Net sales 48.0 35.8 36.3
Europe Building Products | Fiber gypsum revenues      
Segment Reporting, Revenue Reconciling Item [Line Items]      
Net sales 323.4 332.5 0.0
Europe Building Products | Other revenues      
Segment Reporting, Revenue Reconciling Item [Line Items]      
Net sales 0.0 0.0 0.0
Other Businesses      
Segment Reporting, Revenue Reconciling Item [Line Items]      
Net sales 0.6 14.6 14.7
Other Businesses | Fiber cement revenues      
Segment Reporting, Revenue Reconciling Item [Line Items]      
Net sales 0.0 0.0 0.0
Other Businesses | Fiber gypsum revenues      
Segment Reporting, Revenue Reconciling Item [Line Items]      
Net sales 0.0 0.0 0.0
Other Businesses | Other revenues      
Segment Reporting, Revenue Reconciling Item [Line Items]      
Net sales $ 0.6 $ 14.6 $ 14.7