Stock-Based Compensation (Schedule Of Stock Option Activity) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Apr. 30, 2014	Apr. 30, 2013	Apr. 30, 2012	Apr. 30, 2011
Stock-Based Compensation [Abstract]
Oustanding number of options, Beginning Balance	1,401,813	1,624,760	1,605,356
Options granted	60,500	125,000	130,000
Options exercised	(551,485)	(251,799)	(1,200)
Options cancelled or expired	(59,514)	(96,148)	(109,396)
Oustanding number of options ending balance	851,314	1,401,813	1,624,760	1,605,356
Remaining contractual term outstanding	4 years 3 months 18 days	4 years 9 months 18 days	5 years 1 month 6 days	5 years 8 months 12 days
Remaining contractual term, granted	9 years 1 month 6 days	9 years 1 month 6 days	9 years 1 month 6 days
Exercise price, beginning	$ 27.27	$ 27.64	$ 28.48
Exercise price, granted	$ 36.74	$ 17.62	$ 18.16
Exercise price, exercised	$ 26.61	$ 23.35	$ 14.93
Exercise price, cancelled or expired	$ 30.17	$ 31.03	$ 28.82
Exercise price, ending	$ 28.16	$ 27.27	$ 27.64	$ 28.48
Aggregate intrinsic value outstanding, beginning balance	$ 9,272	$ 0	$ 29
Aggregate intrinsic value outstanding, ending balance	3,121	9,272	0	29
Aggregate intrinsic value, exercised	5,156	1,868	6
Vested and expected to vest in the future, Number of options	836,259
Vested and expected to vest in the future, Remaining contractual term	4 years 2 months 12 days
Vested and expected to vest in the future, Exercise price	$ 28.24
Vested and expected to vest in the future, Aggregate intrinsic value	2,995
Exercisable, Number of options	699,412
Exercisable, Remaining contractual term	3 years 4 months 24 days
Exercisable, Exercise price	$ 29.00
Exercisable, Aggregate intrinsic value	$ 1,900