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

Operating Segment Information and Concentrations of Risk - Summary of Geographical Information 2 (Detail)

v3.19.1
Operating Segment Information and Concentrations of Risk - Summary of Geographical Information 2 (Detail)
$ in Millions, $ in Millions
3 Months Ended 12 Months Ended
Dec. 31, 2017
USD ($)
Dec. 31, 2017
AUD ($)
Mar. 31, 2019
USD ($)
Mar. 31, 2018
USD ($)
Mar. 31, 2017
USD ($)
Segment Reporting Information [Line Items]          
Research and development costs     $ 37.9 $ 33.3 $ 30.3
Selling, general and administrative expenses     403.6 311.3 291.6
Asbestos adjustments $ (43.6) $ (56.8) (22.0) (156.4) 40.4
AICF SG&A expenses     (1.5) (1.9) (1.5)
Net interest (income) expense     50.1 29.5 27.5
Asset impairments     15.9 0.0 0.0
Disposed of by Sale | Fontana Building | Buildings          
Segment Reporting Information [Line Items]          
Gain from disposition     0.0 3.4 0.0
General Corporate          
Segment Reporting Information [Line Items]          
Asbestos adjustments     (22.0) (156.4) 40.4
Value of Asbestos-related assets     486.8 537.7  
North America Fiber Cement          
Segment Reporting Information [Line Items]          
Research and development costs     6.5 6.1 6.2
Asset impairments     3.0 0.0 0.0
Asia Pacific Fiber Cement          
Segment Reporting Information [Line Items]          
Research and development costs     2.1 1.8 1.5
Europe Building Products          
Segment Reporting Information [Line Items]          
Research and development costs     2.6 0.0 0.0
Research and Development          
Segment Reporting Information [Line Items]          
Research and development costs     26.7 25.4 22.6
Selling, general and administrative expenses     2.3 2.4 2.9
AICF Funding          
Segment Reporting Information [Line Items]          
Net interest (income) expense     (2.0) (1.9) 1.1
Asia Pacific          
Segment Reporting Information [Line Items]          
New Zealand weathertightness claims (expense)/ benefit     3.3 0.0 0.0
Other Businesses          
Segment Reporting Information [Line Items]          
Asset impairments     12.9 0.0 0.0
Fermacell          
Segment Reporting Information [Line Items]          
Business Acquisition, Transaction Costs     0.0 $ 10.0 $ 0.0
Transaction and integration related costs     21.8    
Inventory fair value adjustment     7.3    
Goodwill | North America Fiber Cement          
Segment Reporting Information [Line Items]          
Asset impairments     0.0    
Goodwill | Other Businesses          
Segment Reporting Information [Line Items]          
Asset impairments     4.6    
Property, Plant and Equipment | North America Fiber Cement          
Segment Reporting Information [Line Items]          
Asset impairments     2.6    
Property, Plant and Equipment | Other Businesses          
Segment Reporting Information [Line Items]          
Asset impairments     6.1    
Finite-Lived Intangible Assets | North America Fiber Cement          
Segment Reporting Information [Line Items]          
Asset impairments     0.4    
Finite-Lived Intangible Assets | Other Businesses          
Segment Reporting Information [Line Items]          
Asset impairments     $ 2.2