Stock-Based Compensation (Schedule Of Stock Option Activity) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Apr. 30, 2020	Apr. 30, 2019	Apr. 30, 2018	Apr. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Oustanding number of options, Beginning Balance	5,167	17,968	54,918
Options exercised	(5,167)	(12,801)	(36,950)
Oustanding number of options ending balance	0	5,167	17,968	54,918
Remaining contractual term outstanding	0 years	6 years 1 month 6 days	4 years 6 months	5 years 7 months 6 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Exercise price, beginning	$ 57.11	$ 44.23	$ 37.95
Exercise price, exercised	57.11	39.04	34.90
Exercise price, ending	$ 0	$ 57.11	$ 44.23	$ 37.95
Aggregate intrinsic value outstanding, beginning balance	$ 170	$ 682	$ 2,963
Aggregate intrinsic value, exercised	0	651	1,748
Aggregate intrinsic value outstanding, ending balance	$ 0	$ 170	$ 682	$ 2,963
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest [Abstract]
Vested and expected to vest in the future, Number of options	0
Vested and expected to vest in the future, Remaining contractual term	0 years
Vested and expected to vest in the future, Exercise price	$ 0
Vested and expected to vest in the future, Aggregate intrinsic value	$ 0
Exercisable, Number of options	0
Exercisable, Remaining contractual term	0 years
Exercisable, Exercise price	$ 0
Exercisable, Aggregate intrinsic value	$ 0