Stock-Based Compensation (Assumptions Used To Value Options) (Details) (USD $)	12 Months Ended
	Apr. 30, 2012 Y		Apr. 30, 2011 Y	Apr. 30, 2010 Y
Options-Management And Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility, minimum	31.75%		28.98%	27.11%
Expected volatility, maximum	32.34%		30.20%	27.27%
Expected term, years	5		5	5
Dividend yield, minimum	3.43%		4.18%	3.24%
Dividend yield, maximum	4.80%		5.17%	3.55%
Risk-free interest rate, minimum	0.79%		1.26%	2.38%
Risk-free interest rate, maximum	1.95%		1.92%	2.75%
Weighted-average fair value	$ 3.31		$ 2.25	$ 3.27
Options-Seasonal [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility				33.81%	[1]
Expected term, years				2	[1]
Dividend yield				3.48%	[1]
Risk-free interest rate				0.85%	[1]
Weighted-average fair value				$ 2.70	[1]
ESPP Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility, minimum	24.27%		22.75%	23.68%
Expected volatility, maximum	33.07%		23.31%	43.20%
Expected term, years	0.5		0.5	0.5
Dividend yield, minimum	3.68%		3.86%	2.65%
Dividend yield, maximum	4.93%		4.80%	3.46%
Risk-free interest rate, minimum	0.06%		0.19%	0.20%
Risk-free interest rate, maximum	0.10%		0.23%	0.33%
Weighted-average fair value	$ 2.78		$ 2.16	$ 3.66
Performance-Based Nonvested Share Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility, minimum	20.68%
Expected volatility, maximum	143.12%
Expected term, years	3
Dividend yield	0.00%	[2]
Risk-free interest rate	0.75%
Weighted-average fair value	$ 17.46

[1] This plan was terminated in fiscal year 2010, except for outstanding awards thereunder.

[2] The valuation model assumes that dividends are reinvested by the issuing entity on a continuous basis.