Stock-Based Compensation (Tables)

12 Months Ended

Apr. 30, 2018

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, 2018, 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, 2017	8,278		$	25.74
Granted	1,059		39.07
Exercised	(2,116	)	17.11
Forfeited or expired	(6	)	36.05
Outstanding at April 30, 2018	7,215		$	29.67	5.4	$	190
Exercisable at April 30, 2018	4,335		$	23.17	3.7	$	142

Assumptions used for fair value estimation

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

	2016		2017		2018
Risk-free interest rate	2.1	%	1.4	%	2.2	%
Expected volatility	19.1	%	16.3	%	15.6	%
Expected dividend yield	1.6	%	1.6	%	1.5	%
Expected term (years)	6.75		7.00		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 2018.

	Number of Underlying Shares (in thousands)		Weighted Average Fair Value at Grant Date
Nonvested at April 30, 2017	601		$	36.50
Granted	165		33.68
Adjusted for dividends or performance	43		50.47
Vested	(136	)	34.52
Forfeited	(3	)	39.40
Nonvested at April 30, 2018	670		$	39.84