XML 48 R32.htm IDEA: XBRL DOCUMENT v3.6.0.2
Fair Value Measurement - Additional Information (Detail) - USD ($)
$ in Millions
Jan. 31, 2017
Apr. 30, 2016
Apr. 30, 2015
5.000% Senior Notes due 2018      
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]      
Debt instrument, interest rate 5.00%   5.00%
(Level 1)      
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]      
Cash equivalents $ 54.3 $ 191.3