Short-Term Investments (Details 3) (USD $) In Thousands	Jul. 31, 2011	Jul. 31, 2010
Fair value measurements of the Company's cash, cash equivalents and short-term investments
Total Short-term investments, Fair value	$ 153,185	$ 124,167
Corporate bonds and notes [Member] \| Fair Value, Measurements, Recurring [Member]
Fair value measurements of the Company's cash, cash equivalents and short-term investments
Total Short-term investments, Fair value	42,020	23,867
Corporate bonds and notes [Member] \| Fair Value, Measurements, Recurring [Member] \| Level 1 [Member]
Fair value measurements of the Company's cash, cash equivalents and short-term investments
Total Short-term investments, Fair value	0	0
Corporate bonds and notes [Member] \| Fair Value, Measurements, Recurring [Member] \| Level 2 [Member]
Fair value measurements of the Company's cash, cash equivalents and short-term investments
Total Short-term investments, Fair value	42,020	23,867
U.S. government agency securities [Member] \| Fair Value, Measurements, Recurring [Member]
Fair value measurements of the Company's cash, cash equivalents and short-term investments
Total Short-term investments, Fair value	40,850	80,752
U.S. government agency securities [Member] \| Fair Value, Measurements, Recurring [Member] \| Level 1 [Member]
Fair value measurements of the Company's cash, cash equivalents and short-term investments
Total Short-term investments, Fair value	0	0
U.S. government agency securities [Member] \| Fair Value, Measurements, Recurring [Member] \| Level 2 [Member]
Fair value measurements of the Company's cash, cash equivalents and short-term investments
Total Short-term investments, Fair value	40,850	80,752
U.S. treasury bills [Member] \| Fair Value, Measurements, Recurring [Member]
Fair value measurements of the Company's cash, cash equivalents and short-term investments
Total Short-term investments, Fair value	57,093	12,873
U.S. treasury bills [Member] \| Fair Value, Measurements, Recurring [Member] \| Level 1 [Member]
Fair value measurements of the Company's cash, cash equivalents and short-term investments
Total Short-term investments, Fair value	0	0
U.S. treasury bills [Member] \| Fair Value, Measurements, Recurring [Member] \| Level 2 [Member]
Fair value measurements of the Company's cash, cash equivalents and short-term investments
Total Short-term investments, Fair value	57,093	12,873
Commercial paper [Member] \| Fair Value, Measurements, Recurring [Member]
Fair value measurements of the Company's cash, cash equivalents and short-term investments
Total Short-term investments, Fair value	5,592	4,495
Commercial paper [Member] \| Fair Value, Measurements, Recurring [Member] \| Level 1 [Member]
Fair value measurements of the Company's cash, cash equivalents and short-term investments
Total Short-term investments, Fair value	0	0
Commercial paper [Member] \| Fair Value, Measurements, Recurring [Member] \| Level 2 [Member]
Fair value measurements of the Company's cash, cash equivalents and short-term investments
Total Short-term investments, Fair value	5,592	4,495
Certificates of deposit [Member] \| Fair Value, Measurements, Recurring [Member]
Fair value measurements of the Company's cash, cash equivalents and short-term investments
Total Short-term investments, Fair value	7,630	2,180
Fair Value, Measurements, Recurring [Member]
Fair value measurements of the Company's cash, cash equivalents and short-term investments
Money market funds	16,722	9,895
Total cash equivalents and short-term investments	162,277	131,882
Cash deposits with third party financial institutions	64,051	21,359
Total cash, cash equivalents and short-term investments	233,958	155,421
Fair Value, Measurements, Recurring [Member] \| Level 1 [Member]
Fair value measurements of the Company's cash, cash equivalents and short-term investments
Money market funds	16,722	9,895
Total cash equivalents and short-term investments	16,722	9,895
Fair Value, Measurements, Recurring [Member] \| Level 2 [Member]
Fair value measurements of the Company's cash, cash equivalents and short-term investments
Money market funds	0	0
Total cash equivalents and short-term investments	145,555	121,987
Corporate bonds and notes [Member]
Fair value measurements of the Company's cash, cash equivalents and short-term investments
Total Short-term investments, Fair value	42,020	23,867
U.S. government agency securities [Member]
Fair value measurements of the Company's cash, cash equivalents and short-term investments
Total Short-term investments, Fair value	40,850	80,752
U.S. treasury bills [Member]
Fair value measurements of the Company's cash, cash equivalents and short-term investments
Total Short-term investments, Fair value	57,093	12,873
Commercial paper [Member]
Fair value measurements of the Company's cash, cash equivalents and short-term investments
Total Short-term investments, Fair value	5,592	4,495
Certificates of deposit [Member]
Fair value measurements of the Company's cash, cash equivalents and short-term investments
Total Short-term investments, Fair value	$ 7,630	$ 2,180

Short-Term Investments (Details 3) (USD $)
In Thousands

Jul. 31, 2011

Jul. 31, 2010

Fair value measurements of the Company's cash, cash equivalents and short-term investments

Total Short-term investments, Fair value

$ 153,185

$ 124,167

Corporate bonds and notes [Member] | Fair Value, Measurements, Recurring [Member]

Fair value measurements of the Company's cash, cash equivalents and short-term investments

Total Short-term investments, Fair value

42,020

23,867

Corporate bonds and notes [Member] | Fair Value, Measurements, Recurring [Member] | Level 1 [Member]

Fair value measurements of the Company's cash, cash equivalents and short-term investments

Total Short-term investments, Fair value

Corporate bonds and notes [Member] | Fair Value, Measurements, Recurring [Member] | Level 2 [Member]

Fair value measurements of the Company's cash, cash equivalents and short-term investments

Total Short-term investments, Fair value

42,020

23,867

U.S. government agency securities [Member] | Fair Value, Measurements, Recurring [Member]

Fair value measurements of the Company's cash, cash equivalents and short-term investments

Total Short-term investments, Fair value

40,850

80,752

U.S. government agency securities [Member] | Fair Value, Measurements, Recurring [Member] | Level 1 [Member]

Fair value measurements of the Company's cash, cash equivalents and short-term investments

Total Short-term investments, Fair value

U.S. government agency securities [Member] | Fair Value, Measurements, Recurring [Member] | Level 2 [Member]

Fair value measurements of the Company's cash, cash equivalents and short-term investments

Total Short-term investments, Fair value

40,850

80,752

U.S. treasury bills [Member] | Fair Value, Measurements, Recurring [Member]

Fair value measurements of the Company's cash, cash equivalents and short-term investments

Total Short-term investments, Fair value

57,093

12,873

U.S. treasury bills [Member] | Fair Value, Measurements, Recurring [Member] | Level 1 [Member]

Fair value measurements of the Company's cash, cash equivalents and short-term investments

Total Short-term investments, Fair value

U.S. treasury bills [Member] | Fair Value, Measurements, Recurring [Member] | Level 2 [Member]

Fair value measurements of the Company's cash, cash equivalents and short-term investments

Total Short-term investments, Fair value

57,093

12,873

Commercial paper [Member] | Fair Value, Measurements, Recurring [Member]

Fair value measurements of the Company's cash, cash equivalents and short-term investments

Total Short-term investments, Fair value

5,592

4,495

Commercial paper [Member] | Fair Value, Measurements, Recurring [Member] | Level 1 [Member]

Fair value measurements of the Company's cash, cash equivalents and short-term investments

Total Short-term investments, Fair value

Commercial paper [Member] | Fair Value, Measurements, Recurring [Member] | Level 2 [Member]

Fair value measurements of the Company's cash, cash equivalents and short-term investments

Total Short-term investments, Fair value

5,592

4,495

Certificates of deposit [Member] | Fair Value, Measurements, Recurring [Member]

Fair value measurements of the Company's cash, cash equivalents and short-term investments

Total Short-term investments, Fair value

7,630

2,180

Fair Value, Measurements, Recurring [Member]

Fair value measurements of the Company's cash, cash equivalents and short-term investments

Money market funds

16,722

9,895

Total cash equivalents and short-term investments

162,277

131,882

Cash deposits with third party financial institutions

64,051

21,359

Total cash, cash equivalents and short-term investments

233,958

155,421

Fair Value, Measurements, Recurring [Member] | Level 1 [Member]

Fair value measurements of the Company's cash, cash equivalents and short-term investments

Money market funds

16,722

9,895

Total cash equivalents and short-term investments

16,722

9,895

Fair Value, Measurements, Recurring [Member] | Level 2 [Member]

Fair value measurements of the Company's cash, cash equivalents and short-term investments

Money market funds

Total cash equivalents and short-term investments

145,555

121,987

Corporate bonds and notes [Member]

Fair value measurements of the Company's cash, cash equivalents and short-term investments

Total Short-term investments, Fair value

42,020

23,867

U.S. government agency securities [Member]

Fair value measurements of the Company's cash, cash equivalents and short-term investments

Total Short-term investments, Fair value

40,850

80,752

U.S. treasury bills [Member]

Fair value measurements of the Company's cash, cash equivalents and short-term investments

Total Short-term investments, Fair value

57,093

12,873

Commercial paper [Member]

Fair value measurements of the Company's cash, cash equivalents and short-term investments

Total Short-term investments, Fair value

5,592

4,495

Certificates of deposit [Member]

Fair value measurements of the Company's cash, cash equivalents and short-term investments

Total Short-term investments, Fair value

$ 7,630

$ 2,180

- Definition

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents Available-for-sale Securities which consist of all investments in certain debt and equity securities neither classified as trading or held-to-maturity securities. A debt security represents a creditor relationship with an enterprise. Debt securities include, among other items, US Treasury securities, US government securities, municipal securities, corporate bonds, convertible debt, commercial paper, and all securitized debt instruments. An equity security represents an ownership interest in an enterprise or the right to acquire or dispose of an ownership interest in an enterprise at fixed or determinable prices. Equity securities include, among other things, common stock, certain preferred stock, warrant rights, call options, and put options, but do not include convertible debt. An entity may opt to provide the reader with additional narrative text to better understand the nature of investments in debt and equity securities which are categorized as Available-for-sale.

+ References+ Details