Deferred Compensation And Retirement Plans (Total Long-Term Benefit Obligations) (Detail) - USD ($) $ in Thousands	Apr. 30, 2016	Apr. 30, 2015
Defined Benefit Plan Disclosure [Line Items]
Total benefit obligation	$ 234,059	$ 191,446
Less: current portion of benefit obligation	(17,946)	(18,014)
Non-current benefit obligation	216,113	173,432
Deferred Compensation Plan
Defined Benefit Plan Disclosure [Line Items]
Total benefit obligation	82,546	83,876
Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Total benefit obligation	5,219	5,262
International Retirement Plans
Defined Benefit Plan Disclosure [Line Items]
Total benefit obligation	15,678	2,847
Executive Capital Accumulation Plan
Defined Benefit Plan Disclosure [Line Items]
Total benefit obligation	105,676	$ 99,461
Legacy Hay Group Defined Benefit Obligation Plan
Defined Benefit Plan Disclosure [Line Items]
Total benefit obligation	$ 24,940