Stock Based Compensation (Tables)

12 Months Ended

Apr. 30, 2012

Stock-Based Compensation [Abstract]

Summary of stock options and SSARs granted under the plan

	Number of Underlying Shares (in thousands)			Weighted Average Exercise Price per Award		Weighted Average Remaining Contractual Term (years)		Aggregate Intrinsic Value
Outstanding at May 1, 2011		3,706		$	45.69
Granted		388			73.95
Exercised		(659	)		34.81
Forfeited or expired		(18	)		56.60
Outstanding at April 30, 2012		3,417		$	50.94		5.0	$	121
Exercisable at April 30, 2012		2,217		$	46.57		3.5	$	88

Assumptions used for fair value estimation

	2010			2011			2012
Risk-free interest rate		3.0	%		2.1	%		1.9	%
Expected volatility		22.6	%		23.7	%		23.6	%
Expected dividend yield		1.9	%		1.9	%		1.9	%
Expected life (years)		6			6			6

Summary of changes in outstanding RSUs and restricted stock

	Number of Underlying Shares (in thousands)			Weighted Average Fair Value at Grant Date
Outstanding at May 1, 2011		156		$	53.58
Granted		63			72.40
Vested		(24	)		57.50
Forfeited		(1	)		60.48
Outstanding at April 30, 2012		194		$	59.19