Quarterly Financial Data (Schedule Of Share Price And Dividends Paid) (Details) - $ / shares	3 Months Ended								12 Months Ended
	Apr. 30, 2016	Jan. 31, 2016	Oct. 31, 2015	Jul. 31, 2015	Apr. 30, 2015	Jan. 31, 2015	Oct. 31, 2014	Jul. 31, 2014	Apr. 30, 2016	Apr. 30, 2015
Quarterly Financial Data [Line Items]
Dividends paid per share	$ 0.20	$ 0.20	$ 0.20	$ 0.20	$ 0.20	$ 0.20	$ 0.20	$ 0.20	$ 0.80	$ 0.80
High
Quarterly Financial Data [Line Items]
Stock price range	35.14	37.53	37.50	34.62	35.80	35.09	33.92	33.65	37.53	35.80
Low
Quarterly Financial Data [Line Items]
Stock price range	$ 19.75	$ 31.00	$ 31.03	$ 29.15	$ 30.10	$ 31.41	$ 27.42	$ 27.23	$ 19.75	$ 27.23