Quarterly report pursuant to Section 13 or 15(d)

Components of Net Periodic Benefit Costs (Detail)

v3.3.1.900
Components of Net Periodic Benefit Costs (Detail) - Deferred Compensation Plan - USD ($)
$ in Thousands
3 Months Ended 6 Months Ended
Oct. 31, 2015
Oct. 31, 2014
Oct. 31, 2015
Oct. 31, 2014
Defined Benefit Plan Disclosure [Line Items]        
Amortization of actuarial loss $ 731 $ 762 $ 1,462 $ 1,525
Interest cost 703 748 1,406 1,495
Net periodic benefit costs $ 1,434 $ 1,510 $ 2,868 $ 3,020