| **Consolidated Balance Sheets (Parenthetical) (USD $)In Thousands, except Share data, unless otherwise specified** | Jul. 31, 2012 | Jul. 31, 2011 |
|--------------------------------------------------------------------------------------------------------------------|---------------|---------------|
| **Statement of Financial Position [Abstract]**                                                                     |          |          |
| Trade receivables, allowances                                                                                      | $ 4,553       | $ 3,423       |
| Inventories, reserves                                                                                              | $ 1,864       | $ 1,552       |
| Preferred stock, par value (in dollars per share)                                                                  | $ 0.01        | $ 0.01        |
| Preferred stock, shares authorized                                                                                 | 25,000,000    | 25,000,000    |
| Preferred stock, shares issued                                                                                     | 0             | 0             |
| Preferred stock, shares outstanding                                                                                | 0             | 0             |
| Common stock, par value (in dollars per share)                                                                     | $ 0.01        | $ 0.01        |
| Common stock, shares authorized                                                                                    | 100,000,000   | 100,000,000   |
| Common stock, shares issued                                                                                        | 40,531,204    | 40,334,973    |
| Treasury stock, shares                                                                                             | 4,949,111     | 4,264,804     |

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| - Definition
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.
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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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| - Definition
The maximum number of common shares permitted to be issued by an entity's charter and bylaws.
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| - Definition
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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| - Definition
The amount of the valuation account as of the balance sheet date which reduces the carrying amount of inventory to net realizable value; takes into consideration such factors as market value, excessive quantities based on expected sales, technological obsolescence, and shrinkage. May also provide for estimated product returns or price concessions pertaining to product cost.
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Face amount or stated value per share of nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer); generally not indicative of the fair market value per share.
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| - Definition
The maximum number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) permitted to be issued by an entity's charter and bylaws.
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Total number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) issued to shareholders (includes related preferred shares that were issued, repurchased, and remain in the treasury). May be all or portion of the number of preferred shares authorized. Excludes preferred shares that are classified as debt.
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| - Definition
Aggregate share number for all nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer) held by stockholders. Does not include preferred shares that have been repurchased.
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| - Definition
Number of common and preferred shares that were previously issued and that were repurchased by the issuing entity and held in treasury on the financial statement date. This stock has no voting rights and receives no dividends.
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