Employee Benefit and Retirement Plans (Reconciliation Of Benefit Obligations, Plan Assets, And Funded Status) (Details) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2017	Apr. 30, 2016	Apr. 30, 2015
Compensation and Retirement Disclosure [Abstract]
Projected benefit obligation at beginning of year	$ 174,096	$ 169,986
Interest cost	5,772	7,014	$ 6,466
Acturial (gains) and losses	(4,672)	1,921
Benefits paid	(10,023)	(4,825)
Projected benefit obligation at end of year	165,173	174,096	169,986
Fair value of plan assets at beginning of year	106,965	108,661
Actual return on plan assets	12,895	(1,887)
Company contributions	27,304	5,016
Benefits paid	(10,023)	(4,825)
Fair value of plan assets at end of year	137,141	106,965	$ 108,661
Funded status of the plan	(28,032)	(67,131)
Unrecognized net actuarial loss	66,255	77,514
Prepaid (accrued) benefit cost	$ 38,223	$ 10,383