XML 55 R42.htm IDEA: XBRL DOCUMENT v3.8.0.1
Financial Instruments - Summary of Gains and Losses on Interest Rate Swap (Parenthetical) (Detail) - USD ($)
$ in Thousands
3 Months Ended 6 Months Ended
Oct. 31, 2017
Oct. 31, 2017
Derivative [Line Items]    
Gains recognized in OCI, tax effects $ 200 $ 100
Interest Rate Swap    
Derivative [Line Items]    
Gains recognized in OCI, tax effects $ 205 $ 56