Stock-Based Compensation (Summary of Stock Options) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
Apr. 30, 2011
Stock-Based Compensation
Shares, Outstanding, beginning of the year	15,082
Shares, Granted	2,080
Shares, Exercised	(338)
Shares, Forfeited or expired	(6,034)
Shares, Outstanding, end of the year	10,790
Shares, Exercisable, end of the year	8,122
Shares, Exercisable and expected to vest	10,650
Weighted-Average Exercise Price, Outstanding, beginning of the year	$ 20.58
Weighted-Average Exercise Price, Granted	$ 13.29
Weighted-Average Exercise Price, Exercised	$ 10.64
Weighted-Average Exercise Price, Forfeited or expired	$ 22.17
Weighted-Average Exercise Price, Outstanding, ending of the year	$ 18.64
Weighted-Average Exercise Price, Exercisable, end of the year	$ 19.95
Weighted-Average Exercise Price, Exercisable and expected to vest	$ 18.71
Weighted-Average Remaining Contractual Term, Outstanding, end of the year	4
Weighted-Average Remaining Contractual Term, Exercisable, end of the year	2
Weighted-Average Remaining Contractual Term, Exercisable and expected to vest	4
Aggregate Intrinsic Value, Outstanding, end of the year	$ 9,224
Aggregate Intrinsic Value, Exercisable, end of the year	1,318
Aggregate Intrinsic Value, Exercisable and expected to vest	$ 8,666

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The weighted average price at which option holders acquired shares when converting their stock options into shares under the plan during the reporting period.

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For presentations that combine terminations, the number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan or that expired.

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The combined weighted average exercise price associated with stock options during the period that have either lapsed or been forfeited.

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

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The weighted average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on stock options awarded under the plan during the reporting period.

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The total dollar difference between fair values of the underlying shares reserved for issuance and exercise prices pertaining to options outstanding under the plan as of the balance sheet date.

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The number of shares reserved for issuance under stock option agreements awarded under the plan that validly exist and are outstanding as of the balance sheet date, including vested options.

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The weighted average price as of the beginning of the year at which grantees can acquire the shares reserved for issuance under the stock option plan.

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The weighted average period between the balance sheet date and expiration for all awards outstanding under the plan, which may be expressed in a decimal value for number of years.

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As of the balance sheet date, the total dollar difference between fair values of the underlying shares reserved for issuance and exercise prices of fully vested and expected to vest options that are exercisable.

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The number of exercisable share options (fully vested and expected to vest) that may be converted as of the balance sheet date.

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As of the balance sheet date, the weighted-average exercise price (at which grantees can acquire the shares reserved for issuance) for exercisable stock options that are fully vested or expected to vest.

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The weighted-average period between the balance sheet date and expiration date for fully vested and expected to vest options that are exercisable (or convertible) under the plan, which may be expressed in a decimal value for number of years.

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As of the balance sheet date, the number of shares into which fully vested and expected to vest stock options outstanding can be converted under the option plan.

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As of the balance sheet date, the weighted-average exercise price for outstanding stock options that are fully vested or expected to vest.

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The weighted-average period between the balance sheet date and expiration date for fully vested and expected to vest options outstanding, which may be expressed in a decimal value for number of years.

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Number of share options (or share units) exercised during the current period.

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