Stock-Based Compensation (Tables)

12 Months Ended

Apr. 30, 2017

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Summary of stock options and SSARs granted under the plan

The following table presents information about stock options and stock-settled stock appreciation rights (SSARs) granted under the Plan (or its predecessor plans) as of April 30, 2017, and for the year then ended.

	Number of Underlying Shares (in thousands)		Weighted Average Exercise Price per Award		Weighted Average Remaining Contractual Term (years)	Aggregate Intrinsic Value
Outstanding at April 30, 2016	6,852		$	28.42
Granted	779		49.01
Exercised	(1,005	)	19.49
Forfeited or expired	(11	)	46.79
Outstanding at April 30, 2017	6,615		$	32.17	5.0	$	104
Exercisable at April 30, 2017	4,390		$	23.75	3.6	$	103

Assumptions used for fair value estimation

We estimated the fair values using the Black-Scholes pricing model with the following assumptions:

	2015		2016		2017
Risk-free interest rate	2.2	%	2.1	%	1.4	%
Expected volatility	22.3	%	19.1	%	16.3	%
Expected dividend yield	1.7	%	1.6	%	1.6	%
Expected term (years)	6.75		6.75		7.00

Summary of changes in outstanding RSUs and restricted stock

The following table summarizes the changes in the number of shares underlying these awards during 2017.

	Number of Underlying Shares (in thousands)		Weighted Average Fair Value at Grant Date
Nonvested at April 30, 2016	547		$	42.61
Granted	134		48.44
Adjusted for dividends or performance	(31	)	47.45
Vested	(153	)	36.71
Forfeited	(5	)	44.27
Nonvested at April 30, 2017	492		$	45.71