Stock-Based Compensation (Assumptions Used To Value Options) (Details) (USD $)	12 Months Ended
	Apr. 30, 2014		Apr. 30, 2013		Apr. 30, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term, years	3 years		3 years		3 years
Dividend yield			0.00%	[1]
Espp [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility, minimum	22.32%		24.27%
Expected volatility, maximum	27.39%		33.07%
Dividend yield, minimum	4.20%		3.68%
Dividend yield, maximum	5.00%		4.93%
Risk-free interest rate, minimum	0.11%		0.06%
Risk-free interest rate, maximum	0.15%		0.10%
Stock Options For Management And Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility, minimum	30.89%		29.69%		31.75%
Expected volatility, maximum	31.57%		31.43%		32.34%
Expected term, years			5 years
Dividend yield, minimum	2.77%		4.18%		3.43%
Dividend yield, maximum	2.87%		5.21%		4.80%
Risk-free interest rate, minimum	1.06%		0.61%		0.79%
Risk-free interest rate, maximum	1.31%		0.75%		1.95%
Weighted-average fair value	$ 5.57		$ 2.79		$ 3.31
Performance Nonvested Share Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility, minimum	11.75%		12.61%		20.68%
Expected volatility, maximum	70.17%		71.96%		143.12%
Dividend yield, minimum	0.00%	[1]	0.00%	[1]
Dividend yield, maximum	2.88%	[1]	5.01%	[1]
Risk-free interest rate	0.61%		0.40%		0.75%
Weighted-average fair value	$ 28.59		$ 16.72		$ 17.46
Minimum [Member] | Stock Options For Management And Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term, years			4 years		5 years
Maximum [Member] | Stock Options For Management And Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term, years	4 years		5 years		5 years

[1] The valuation model assumes that dividends are reinvested by the Company on a continuous basis.