Quarterly Financial Data (Schedule Of Share Price And Dividends Paid) (Details) (USD $)	3 Months Ended								12 Months Ended
	Apr. 30, 2015	Jan. 31, 2015	Oct. 31, 2014	Jul. 31, 2014	Apr. 30, 2014	Jan. 31, 2014	Oct. 31, 2013	Jul. 31, 2013	Apr. 30, 2015	Apr. 30, 2014
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	$ 35.80	$ 35.09	$ 33.92	$ 33.65	$ 32.42	$ 30.53	$ 32.09	$ 31.75	$ 35.80	$ 32.42
Low
Quarterly Financial Data [Line Items]
Stock price range	$ 30.10	$ 31.41	$ 27.42	$ 27.23	$ 26.92	$ 27.13	$ 25.98	$ 27.24	$ 27.23	$ 25.98