Annual report pursuant to Section 13 and 15(d)

Deferred Compensation and Retirement Plans (Reconciliation of Fair Value of Plan Assets) (Detail)

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Deferred Compensation and Retirement Plans (Reconciliation of Fair Value of Plan Assets) (Detail) - USD ($)
$ in Thousands
12 Months Ended
Apr. 30, 2017
Apr. 30, 2016
Defined Benefit Plan Disclosure [Line Items]    
Current liability $ 11,443 $ 17,946
Non-current liability 219,905 216,113
Total liability 231,348 234,059
Medical and Life Insurance | Legacy Hay    
Defined Benefit Plan Disclosure [Line Items]    
Benefit obligation, beginning of period 13,006  
Acquisitions   12,322
Service cost 155 62
Interest cost 426 208
Actuarial (gain) loss (833) 816
Benefits paid (607) (402)
Benefit obligation, end of year 12,147 13,006
Current liability 765 673
Non-current liability 11,382 12,333
Total liability $ 12,147 $ 13,006