Stock-Based Compensation (Schedule Of Stock Options Oustanding Activity) (Details) (USD $)	12 Months Ended
	Apr. 30, 2014
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options outstanding	851,314
Options exercisable	699,412
$17.62 - $18.16 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Option price per share, lower range limit	$ 17.62
Option price per share, upper range limit	$ 18.16
Options outstanding	120,002
Options outstanding remaining life	7 years 8 months 12 days
Options outstanding exercise price	$ 17.83
Options exercisable	20,000
Options exercisable exercise price	$ 17.98
$20.87- $26.85 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Option price per share, lower range limit	$ 20.87
Option price per share, upper range limit	$ 26.85
Options outstanding	266,538
Options outstanding remaining life	4 years 6 months
Options outstanding exercise price	$ 23.93
Options exercisable	266,538
Options exercisable exercise price	$ 23.93
$28.97 - $34.63 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Option price per share, lower range limit	$ 28.97
Option price per share, upper range limit	$ 34.63
Options outstanding	412,874
Options outstanding remaining life	2 years 7 months 6 days
Options outstanding exercise price	$ 32.81
Options exercisable	412,874
Options exercisable exercise price	$ 32.81
$36.74 - $36-74 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Option price per share, lower range limit	$ 36.74
Option price per share, upper range limit	$ 36.74
Options outstanding	51,900
Options outstanding remaining life	9 years 1 month 6 days
Options outstanding exercise price	$ 36.74
Options exercisable	0
Options exercisable exercise price	$ 0.00