Employee Stock Plans (Stock Options And SAR Transactions) (Detail) (Stock Options And SARs [Member], USD $)	12 Months Ended
Apr. 30, 2012	Apr. 30, 2011	Apr. 30, 2010
Stock Options And SARs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options, Outstanding, beginning of year	1,833,000	2,723,000	3,113,000
Options, Granted	48,000	211,000	621,000
Options, Exercised	(235,000)	(625,000)	(531,000)
Options, Forfeited/expired	(154,000)	(476,000)	(480,000)
Options, Outstanding, end of year	1,492,000	1,833,000	2,723,000
Options, Exercisable, end of year	1,061,000	1,219,000	2,142,000
Weighted-Average Exercise Price, Outstanding, beginning of year	$ 13.78	$ 14.72	$ 14.83
Weighted-Average Exercise Price, Granted	$ 22.71	$ 13.97	$ 11.26
Weighted-Average Exercise Price, Exercised	$ 12.76	$ 12.81	$ 8.21
Weighted-Average Exercise Price, Forfeited/expired	$ 15.63	$ 20.55	$ 18.14
Weighted-Average Exercise Price, Outstanding, end of year	$ 14.00	$ 13.78	$ 14.72
Weighted-Average Exercise Price, Exercisable, Outstanding, end of year	$ 14.33	$ 14.64	$ 15.68

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The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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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 vested portions of options outstanding and currently exercisable under the stock option plan.

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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 weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated during the reporting period due to noncompliance with plan terms during the reporting period.

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

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