Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Per Share data	Apr. 30, 2011	Apr. 30, 2010
ASSETS
Allowance for doubtful accounts	$ 9,977	$ 5,983
Stockholders' equity:
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	150,000	150,000
Common stock, shares issued	59,101	57,614
Common stock, shares outstanding	47,003	45,979

A valuation allowance for trade and other receivables due to an Entity within one year (or the normal operating cycle, whichever is longer) that are expected to be uncollectible.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Paragraph 4
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Face amount or stated value of common stock per share; generally not indicative of the fair market value per share.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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The maximum number of common shares permitted to be issued by an entity's charter and bylaws.

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Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Regulation S-X (SX)
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-Name Accounting Principles Board Opinion (APB)
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