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

Operating Segment Information and Concentrations of Risk - Summary of Gross Sales by Major Customers (Detail)

v3.7.0.1
Operating Segment Information and Concentrations of Risk - Summary of Gross Sales by Major Customers (Detail) - Customer A [Member] - North America Fiber Cement [Member] - Sales [Member] - Customer Concentration Risk [Member] - USD ($)
$ in Millions
12 Months Ended
Mar. 31, 2017
Mar. 31, 2016
Mar. 31, 2015
Segment Reporting Information [Line Items]      
Gross Sales of Major Customers $ 226.0 $ 197.0 $ 177.4
Gross sales percentage 10.30% 10.10% 10.70%