Fair Value Measurements and Financial Instruments	6 Months Ended
Fair Value Measurements and Financial Instruments	Jan. 31, 2012
Fair Value Measurements and Financial Instruments [Abstract]
Fair Value Measurements and Financial Instruments	(5) Fair Value Measurements and Financial Instruments In accordance with FASB ASC 825, "Financial Instruments," we determined that, as of January 31, 2012 and July 31, 2011, the fair value of our 3.0% convertible senior notes was approximately $221,080,000 and $207,680,000, respectively, based on a quoted market price in an active market. Our 3.0% convertible senior notes are not marked-to-market and are shown in our accompanying Condensed Consolidated Balance Sheets at their original issuance value. As such, changes in the estimated fair value of our 3.0% convertible senior notes are not recorded in our condensed consolidated financial statements. As of January 31, 2012 and July 31, 2011, we had approximately $104,068,000 and $152,878,000, respectively, of money market mutual funds which are classified as cash and cash equivalents in our Condensed Consolidated Balance Sheets. These money market mutual funds are recorded at their current fair value. FASB ASC 820, "Fair Value Measurements and Disclosures," requires us to define fair value as the price that would be received from the sale of an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. As such, using the fair value hierarchy described in FASB ASC 820, we valued our money market mutual funds using Level 1 inputs that were based on quoted market prices. As of January 31, 2012 and July 31, 2011, we had no other assets included in our Condensed Consolidated Balance Sheets that are recorded at current fair value. If we acquire different types of assets or incur different types of liabilities in the future, we might be required to use different FASB ASC fair value methodologies.

Tabular disclosure of the fair value measurement of assets and liabilities which includes [financial] instruments measured at fair value that are classified in stockholders' equity. Such assets and liabilities may be measured on a recurring or nonrecurring basis. The disclosures which may be required or desired include: (1) for assets and liabilities measured on a recurring basis, disclosure may include: (a) the fair value measurements at the reporting date; (b) the level within the fair value hierarchy in which the fair value measurements in their entirety fall, segregating fair value measurements using quoted prices in active markets for identical assets or liabilities (Level 1), significant other observable inputs (Level 2), and significant unobservable inputs (Level 3); (c) for fair value measurements using significant unobservable inputs (Level 3), a reconciliation of the beginning and ending balances, separately presenting changes during the period attributable to the following: (i) total gains or losses for the period (realized and unrealized), segregating those gains or losses included in earnings (or changes in net assets), and a description of where those gains or losses included in earnings (or changes in net assets) are reported in the statement of income (or activities); (ii) purchases, sales, issuances, and settlements (net); (iii) transfers in and transfers out of Level 3 (for example, transfers due to changes in the observability of significant inputs); (d) the amount of the total gains or losses for the period in subparagraph (c) (i) above included in earnings (or changes in net assets) that are attributable to the change in unrealized gains or losses relating to those assets and liabilities still held at the reporting date and a description of where those unrealized gains or losses are reported in the statement of income (or activities); (e) the valuation technique(s) used to measure fair value and a discussion of changes in valuation techniques, if any, during the period and (2) for assets and liabilities that are measured at fair value on a nonrecurring basis (for example, impaired assets) disclosure may include, in addition to (a) above: (a) the reasons for the fair value measurements recorded; (b) the same as (b) above; (c) for fair value measurements using significant unobservable inputs (Level 3), a description of the inputs and the information used to develop the inputs; and (d) the valuation technique(s) used to measure fair value and a discussion of changes, if any, in the valuation technique(s) used to measure similar assets and/or liabilities in prior periods. Where the quoted price in an active market for the identical liability is not available, the Level 1 input is the quoted price of an identical liability when traded as an asset.

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