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

Operating Segment Information and Concentrations of Risk - Operating Segments and Geographical Information (Parenthetical) (Detail)

v3.4.0.3
Operating Segment Information and Concentrations of Risk - Operating Segments and Geographical Information (Parenthetical) (Detail) - USD ($)
$ in Millions
12 Months Ended
Mar. 31, 2016
Mar. 31, 2015
Mar. 31, 2014
Segment Reporting Information [Line Items]      
Research and development costs $ 29.5 $ 31.7 $ 33.1
Selling, general and administrative expenses 254.2 245.5 224.4
Asbestos adjustments (5.5) (33.4) 195.8
AICF SG&A expenses 1.7 2.5 2.1
Net interest (expense) income (25.6) (7.5) (1.1)
General Corporate [Member]      
Segment Reporting Information [Line Items]      
Asbestos adjustments 5.5 33.4 (195.8)
Value of Asbestos-related assets 619.8 657.3  
Asia Pacific Fiber Cement [Member]      
Segment Reporting Information [Line Items]      
Research and development costs 1.2 1.4 1.3
New Zealand weathertightness claims (expense) / benefit (0.5) 4.3 (1.8)
Research and Development [Member]      
Segment Reporting Information [Line Items]      
Research and development costs 21.7 24.2 22.2
Selling, general and administrative expenses 2.2 1.8 2.2
AICF Funding [Member]      
Segment Reporting Information [Line Items]      
Net interest (expense) income 0.3 (1.4) (2.9)
Australian Pipes Business [Member]      
Segment Reporting Information [Line Items]      
Gain on sale of business 1.7    
North America & Europe Fiber Cement [Member]      
Segment Reporting Information [Line Items]      
Research and development costs $ 6.6 $ 6.1 $ 9.6