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 (Detail)

v3.8.0.1
Operating Segment Information and Concentrations of Risk - Summary of Geographical Information (Detail) - USD ($)
$ in Millions
 12 Months Ended
Mar. 31, 2018
Mar. 31, 2017
Mar. 31, 2016
Segment Reporting Information [Line Items]      
Net sales $ 2,054.5 $ 1,921.6 $ 1,728.2
Total Identifiable Assets 2,351.0 2,012.7  
Operating Segments [Member]      
Segment Reporting Information [Line Items]      
Total Identifiable Assets 1,459.9 1,293.8  
General Corporate [Member]      
Segment Reporting Information [Line Items]      
Total Identifiable Assets 891.1 718.9  
North America [Member]      
Segment Reporting Information [Line Items]      
Net sales 1,592.8 1,509.9 1,348.8
North America [Member] | Operating Segments [Member]      
Segment Reporting Information [Line Items]      
Total Identifiable Assets 1,103.6 953.1  
Australia [Member]      
Segment Reporting Information [Line Items]      
Net sales 301.1 252.5 228.4
Australia [Member] | Operating Segments [Member]      
Segment Reporting Information [Line Items]      
Total Identifiable Assets 242.6 237.0  
New Zealand [Member]      
Segment Reporting Information [Line Items]      
Net sales 76.8 73.3 61.4
New Zealand [Member] | Operating Segments [Member]      
Segment Reporting Information [Line Items]      
Total Identifiable Assets 34.8 31.8  
Other Countries [Member]      
Segment Reporting Information [Line Items]      
Net sales 83.8 85.9 $ 89.6
Other Countries [Member] | Operating Segments [Member]      
Segment Reporting Information [Line Items]      
Total Identifiable Assets $ 78.9 $ 71.9