Stock-Based Compensation (Tables)

12 Months Ended

Apr. 30, 2011

Stock-based Compensation [Abstract]

Summary of stock options and SSARs granted under the plan

						Weighted
	Number of			Weighted		Average
	Underlying			Average		Remaining
	Shares			Exercise Price		Contractual		Aggregate
	(in thousands)			per Award		Term (years)		Intrinsic Value
Outstanding at May 1, 2010		4,051		$	41.31
Granted		415			61.24
Exercised		(738	)		30.26
Forfeited or expired		(22	)		49.52
Outstanding at April 30, 2011		3,706		$	45.69		5.0	$	97
Exercisable at April 30, 2011		2,470		$	41.77		3.6	$	74

Assumptions used for fair value estimation

	2009			2010			2011
Risk-free interest rate		3.5	%		3.0	%		2.1	%
Expected volatility		18.1	%		22.6	%		23.7	%
Expected dividend yield		1.8	%		1.9	%		1.9	%
Expected life (years)		6			6			6

Summary of changes in outstanding RSUs and restricted stock

	Number of
	Underlying Shares			Weighted Average
	(in thousands)			Fair Value at Grant Date
Outstanding at May 1, 2010		176		$	50.59
Granted		28			61.14
Vested		(122	)		51.21
Outstanding at April 30, 2011		82		$	53.28