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Short-Term Investments - Cost Basis and Fair Value of Debt Securities by Contractual Maturity (Detail) (USD $)
In Thousands, unless otherwise specified |
Jan. 31, 2015
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Jul. 31, 2014
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|---|---|---|
| Investments, Debt and Equity Securities [Abstract] | ||
| One year or less, Cost Basis | $ 75,684 | $ 110,184 |
| Over one year and less than two years, Cost Basis | 63,313 | 56,131 |
| Total short-term investments, Cost Basis | 138,997 | 166,315 |
| One year or less, Fair Value | 75,709 | 110,280 |
| Over one year and less than two years, Fair Value | 63,340 | 56,079 |
| Total short-term investments, Fair Value | $ 139,049 | $ 166,359 |