Stock-Based Compensation (Schedule Of Stock Option Activity) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Apr. 30, 2017	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		17,968	54,918	126,633
Options exercised		(12,801)	(36,950)	(71,715)
Oustanding number of options ending balance	54,918	5,167	17,968	54,918
Remaining contractual term outstanding	5 years 9 months 18 days	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		$ 44.23	$ 37.95	$ 35.15
Exercise price, exercised		39.04	34.90	33.00
Exercise price, ending	$ 37.95	$ 57.11	$ 44.23	$ 37.95
Aggregate intrinsic value outstanding, beginning balance		$ 682	$ 2,963	$ 4,773
Aggregate intrinsic value, exercised		651	1,748	2,597
Aggregate intrinsic value outstanding, ending balance	$ 2,963	$ 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		5,167
Vested and expected to vest in the future, Remaining contractual term		6 years 1 month 6 days
Vested and expected to vest in the future, Exercise price		$ 57.11
Vested and expected to vest in the future, Aggregate intrinsic value		$ 170
Exercisable, Number of options		5,167
Exercisable, Remaining contractual term		6 years 1 month 6 days
Exercisable, Exercise price		$ 57.11
Exercisable, Aggregate intrinsic value		$ 170