Employee Stock Plans (Outstanding Stock Options And SARs) (Detail) shares in Thousands	12 Months Ended
	Apr. 30, 2016 $ / shares shares
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Shares | shares	105
Options Outstanding, Weighted-Average Remaining Contractual Life (in years)	1 year
Options Outstanding, Weighted-Average Exercise Price	$ 15.01
Options Exercisable, Shares | shares	105
Options Exercisable, Weighted-Average Remaining Contractual Life (in years)	1 year
Options Exercisable, Weighted-Average Exercise Price	$ 15.01
$ 9.75 - $ 13.82
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, Minimum	9.75
Range of Exercise Prices, Maximum	$ 13.82
Options Outstanding, Shares | shares	19
Options Outstanding, Weighted-Average Remaining Contractual Life (in years)	3 months 18 days
Options Outstanding, Weighted-Average Exercise Price	$ 10.40
Options Exercisable, Shares | shares	19
Options Exercisable, Weighted-Average Remaining Contractual Life (in years)	3 months 18 days
Options Exercisable, Weighted-Average Exercise Price	$ 10.40
$13.83 - $ 18.04
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, Minimum	13.83
Range of Exercise Prices, Maximum	$ 18.04
Options Outstanding, Shares | shares	64
Options Outstanding, Weighted-Average Remaining Contractual Life (in years)	1 year 2 months 12 days
Options Outstanding, Weighted-Average Exercise Price	$ 14.06
Options Exercisable, Shares | shares	64
Options Exercisable, Weighted-Average Remaining Contractual Life (in years)	1 year 2 months 12 days
Options Exercisable, Weighted-Average Exercise Price	$ 14.06
$18.05 - $ 22.71
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, Minimum	18.05
Range of Exercise Prices, Maximum	$ 22.71
Options Outstanding, Shares | shares	22
Options Outstanding, Weighted-Average Remaining Contractual Life (in years)	1 year 2 months 12 days
Options Outstanding, Weighted-Average Exercise Price	$ 21.73
Options Exercisable, Shares | shares	22
Options Exercisable, Weighted-Average Remaining Contractual Life (in years)	1 year 2 months 12 days
Options Exercisable, Weighted-Average Exercise Price	$ 21.73