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

Stock-Based Compensation - Schedule of Stock-Based Compensation Expense (Detail)

v3.4.0.3
Stock-Based Compensation - Schedule of Stock-Based Compensation Expense (Detail) - USD ($)
$ in Millions
12 Months Ended
Mar. 31, 2016
Mar. 31, 2015
Mar. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]      
Total stock-based compensation expense $ 15.1 $ 12.5 $ 13.0
Liability Awards Expense [Member]      
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]      
Total stock-based compensation expense 4.8 3.3 4.5
Equity Awards Expense [Member]      
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]      
Total stock-based compensation expense $ 10.3 $ 9.2 $ 8.5