Stock-Based Compensation (Summary Of Nonvested Shares) (Details) - $ / shares shares in Thousands	12 Months Ended
Apr. 30, 2021	Apr. 30, 2020	Apr. 30, 2019
Restricted Share Units and Deferred Stock Units
Shares
Outstanding, beginning of the year (in shares)	2,080
Granted (in shares)	1,328
Released (in shares)	(525)
Forfeited (in shares)	(259)
Outstanding, end of the year (in shares)	2,624	2,080
Weighted-Average Grant Date Fair Value
Outstanding, beginning of the year (in usd per share)	$ 25.94
Granted (in usd per share)	15.58
Released (in usd per share)	27.13
Forfeited (in usd per share)	21.83
Outstanding, end of the year (in usd per share)	$ 21.34	$ 25.94
Performance-Based Nonvested Share Units
Weighted-Average Grant Date Fair Value
Expected volatility, minimum	21.14%	13.47%	13.16%
Expected volatility, maximum	84.49%	66.33%	66.47%
Risk-free interest rate		1.70%	2.61%
Performance-Based Nonvested Share Units \| Minimum
Weighted-Average Grant Date Fair Value
Dividend yield	0.00%	0.00%	0.00%
Performance-Based Nonvested Share Units \| Maximum
Weighted-Average Grant Date Fair Value
Dividend yield	3.95%	3.55%	4.39%
Nonvested Shares And Performance Nonvested
Shares
Outstanding, beginning of the year (in shares)	1,245
Granted (in shares)	949
Released (in shares)	(77)
Forfeited (in shares)	(129)
Outstanding, end of the year (in shares)	1,988	1,245
Weighted-Average Grant Date Fair Value
Outstanding, beginning of the year (in usd per share)	$ 29.12
Granted (in usd per share)	16.74
Released (in usd per share)	24.19
Forfeited (in usd per share)	19.16
Outstanding, end of the year (in usd per share)	$ 21.88	$ 29.12

The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

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Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event.

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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 number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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Per share or unit weighted-average fair value of nonvested award under share-based payment arrangement. Excludes share and unit options.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

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The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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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 maximum 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 estimated measure of the minimum 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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