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)

v3.8.0.1
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, 2018
USD ($)
Mar. 31, 2017
USD ($)
Mar. 31, 2016
USD ($)
Segment Reporting Information [Line Items]          
Research and development costs     $ 33.3 $ 30.3 $ 29.5
Selling, general and administrative expenses     311.3 291.6 254.2
Asbestos adjustments $ (43.6) $ (56.8) (156.4) 40.4 5.5
AICF SG&A expenses     (1.9) (1.5) (1.7)
Net interest (income) expense     29.5 27.5 25.6
Disposed of by Sale [Member] | Fontana Building [Member] | Building [Member]          
Segment Reporting Information [Line Items]          
Gain from disposition     3.4    
General Corporate [Member]          
Segment Reporting Information [Line Items]          
Asbestos adjustments     (156.4) 40.4 5.5
Value of Asbestos-related assets     537.7 573.8  
North America Fiber Cement [Member]          
Segment Reporting Information [Line Items]          
Research and development costs     6.1 6.2 6.6
International Fiber Cement [Member]          
Segment Reporting Information [Line Items]          
Research and development costs     1.8 1.5 1.2
New Zealand weathertightness claims (expense)/ benefit     0.0 0.0 (0.5)
Research and Development [Member]          
Segment Reporting Information [Line Items]          
Research and development costs     25.4 22.6 21.7
Selling, general and administrative expenses     2.4 2.9 2.2
AICF Funding [Member]          
Segment Reporting Information [Line Items]          
Asbestos adjustments     (0.8)    
Net interest (income) expense     $ (1.9) 1.1 $ 0.3
Australian Pipes Business [Member]          
Segment Reporting Information [Line Items]          
Gain on sale of business       $ 1.7