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 (Detail)

v3.4.0.3
Operating Segment Information and Concentrations of Risk - Operating Segments and Geographical Information (Detail) - USD ($)
$ in Millions
 12 Months Ended
Mar. 31, 2016
Mar. 31, 2015
Mar. 31, 2014
Segment Reporting Information [Line Items]      
Net sales $ 1,728.2 $ 1,656.9 $ 1,493.8
Total operating income 354.0 335.0 53.1
Net interest expense (25.6) (7.5) (1.1)
Other income (expense) 2.1 (4.9) 2.6
Total Identifiable Assets 2,040.4 2,044.5  
General Corporate [Member]      
Segment Reporting Information [Line Items]      
Total operating income (43.6) (19.0) (240.6)
Total Identifiable Assets 785.4 784.7  
Asia Pacific Fiber Cement [Member]      
Segment Reporting Information [Line Items]      
Net sales 341.9 380.4 366.2
Total operating income 80.9 94.1 81.1
Total Identifiable Assets 297.4 279.8  
Research and Development [Member]      
Segment Reporting Information [Line Items]      
Total operating income (23.9) (26.0) (24.4)
Total Identifiable Assets 13.6 20.7  
North America & Europe Fiber Cement [Member]      
Segment Reporting Information [Line Items]      
Net sales 1,386.3 1,276.5 1,127.6
Total operating income 340.6 285.9 237.0
Total Identifiable Assets 944.0 959.3  
Australia [Member]      
Segment Reporting Information [Line Items]      
Net sales 228.4 267.7 259.2
Total Identifiable Assets 232.4 223.4  
New Zealand [Member]      
Segment Reporting Information [Line Items]      
Net sales 61.4 64.7 63.0
Total Identifiable Assets 26.5 25.8  
Other Countries [Member]      
Segment Reporting Information [Line Items]      
Net sales 89.6 86.0 77.0
Total Identifiable Assets 71.0 54.2  
Segments Total [Member]      
Segment Reporting Information [Line Items]      
Total operating income 397.6 354.0 293.7
Total Identifiable Assets 1,255.0 1,259.8  
Worldwide Total [Member]      
Segment Reporting Information [Line Items]      
Net sales 1,728.2 1,656.9 1,493.8
Total operating income 330.5 322.6 54.6
Total Identifiable Assets 2,040.4 2,044.5  
North America [Member]      
Segment Reporting Information [Line Items]      
Net sales 1,348.8 1,238.5 $ 1,094.6
Total Identifiable Assets $ 925.1 $ 956.4