Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

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The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

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The risk-free interest rate assumption that is used in valuing an option on its own shares.

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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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Net number of share options (or share units) granted during the period.

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The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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Expected term of share-based compensation awards, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Accounting for Stock-Based Compensation (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended		3 Months Ended
	Jul. 31, 2018	Jun. 30, 2018	Aug. 31, 2018	Aug. 31, 2017
Assumptions used in the Black-Scholes option pricing models to estimate the fair value of each stock option grant
Risk-free interest rate			2.70%
Expected volatility of common stock			30.80%
Dividend yield			0.60%
Expected option term in years			4 years 6 months
Restricted stock
Stock options, additional disclosures
Compensation expense			$ 2.8	$ 1.4
Performance-based restricted stock
Stock options, additional disclosures
Granted (in shares)			43,680
Granted (in dollars per share)			$ 48.09
Time-based restricted stock
Stock options, additional disclosures
Granted (in shares)			38,760
Granted (in dollars per share)			$ 48.09
Time-based restricted stock \| Board of Directors
Stock options, additional disclosures
Granted (in shares)		29,128
Granted (in dollars per share)		$ 45.32
Stock options
Stock options, additional disclosures
Granted (in shares)	290,340
Granted (in dollars per share)	$ 48.09
Weighted average fair value of stock options granted (in dollars per share)	$ 13.67
Total intrinsic value of stock options exercised			$ 10.7	5.0
Compensation expense			$ 1.2	$ 1.1