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

Property, Plant and Equipment - Components of Property, Plant and Equipment 2 (Detail)

v3.20.1
Property, Plant and Equipment - Components of Property, Plant and Equipment 2 (Detail) - USD ($)
$ in Millions
 12 Months Ended
Mar. 31, 2020
Mar. 31, 2019
Mar. 31, 2018
Property, Plant and Equipment [Line Items]      
Capitalized interest $ 9.5 $ 5.4 $ 4.8
Operating lease right-of-use-assets 40.5 0.0  
Net book value of disposals 15.0 28.0  
Net book value of disposals, usage of replacement parts 11.7 13.7  
Net book value of disposals, disposal of assets no longer in use 3.3 5.2  
Held-for-sale      
Property, Plant and Equipment [Line Items]      
Buildings held for sale   5.8  
Cost of Sales      
Property, Plant and Equipment [Line Items]      
Impairment of long-lived assets   0.4  
North America Fiber Cement      
Property, Plant and Equipment [Line Items]      
Operating lease right-of-use-assets $ (0.8)    
Impairment of long-lived assets   2.6  
Other Businesses      
Property, Plant and Equipment [Line Items]      
Impairment of long-lived assets   $ 6.1