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)

v3.19.1
Property, Plant and Equipment - Components of Property, Plant and Equipment 2 (Detail) - USD ($)
$ in Millions
 12 Months Ended
Mar. 31, 2019
Mar. 31, 2018
Mar. 31, 2017
Property, Plant and Equipment [Line Items]      
Capitalized interest $ 5.4 $ 4.8 $ 2.0
Net book value of disposals 28.0 16.4  
Net book value of disposals, usage of replacement parts 13.7 13.9  
Impairment of Long-Lived Assets to be Disposed of 9.1 0.7 0.5
Net book value of disposals, disposal of assets no longer in use 5.2 1.8  
Held-for-sale [Member] | Buildings      
Property, Plant and Equipment [Line Items]      
Buildings held for sale 5.8    
Cost of Sales [Member]      
Property, Plant and Equipment [Line Items]      
Impairment of Long-Lived Assets to be Disposed of 0.4 $ 0.7 $ 0.5
North America Fiber Cement      
Property, Plant and Equipment [Line Items]      
Impairment of Long-Lived Assets to be Disposed of 6.1    
Other Businesses      
Property, Plant and Equipment [Line Items]      
Impairment of Long-Lived Assets to be Disposed of $ 2.6