FAIR VALUE MEASUREMENTS - Fair Value of Financial Assets and Liabilities (Details) - USD ($) $ in Thousands	Oct. 31, 2020	Jul. 31, 2020
Financial Assets:
Short-term investments:	$ 813,603	$ 401,041
Recurring
Financial Assets:
Total measured at fair value	1,116,495	552,976
Cash	201,590	166,802
Total cash, cash equivalents and short-term investments	1,318,085	719,778
Recurring \| Corporate bonds
Financial Assets:
Short-term investments:	532,904	345,265
Recurring \| Commercial paper
Financial Assets:
Short-term investments:	151,267	29,702
Recurring \| U.S. government securities
Financial Assets:
Short-term investments:	129,432	26,074
Recurring \| Money market funds
Financial Assets:
Cash equivalents:	260,398	142,936
Recurring \| Commercial paper
Financial Assets:
Cash equivalents:	42,494	8,999
Recurring \| Level I
Financial Assets:
Total measured at fair value	260,398	142,936
Recurring \| Level I \| Corporate bonds
Financial Assets:
Short-term investments:	0	0
Recurring \| Level I \| Commercial paper
Financial Assets:
Short-term investments:	0	0
Recurring \| Level I \| U.S. government securities
Financial Assets:
Short-term investments:	0	0
Recurring \| Level I \| Money market funds
Financial Assets:
Cash equivalents:	260,398	142,936
Recurring \| Level I \| Commercial paper
Financial Assets:
Cash equivalents:	0	0
Recurring \| Level II
Financial Assets:
Total measured at fair value	856,097	410,040
Recurring \| Level II \| Corporate bonds
Financial Assets:
Short-term investments:	532,904	345,265
Recurring \| Level II \| Commercial paper
Financial Assets:
Short-term investments:	151,267	29,702
Recurring \| Level II \| U.S. government securities
Financial Assets:
Short-term investments:	129,432	26,074
Recurring \| Level II \| Money market funds
Financial Assets:
Cash equivalents:	0	0
Recurring \| Level II \| Commercial paper
Financial Assets:
Cash equivalents:	42,494	8,999
Recurring \| Level III
Financial Assets:
Total measured at fair value	0	0
Recurring \| Level III \| Corporate bonds
Financial Assets:
Short-term investments:	0	0
Recurring \| Level III \| Commercial paper
Financial Assets:
Short-term investments:	0	0
Recurring \| Level III \| U.S. government securities
Financial Assets:
Short-term investments:	0	0
Recurring \| Level III \| Money market funds
Financial Assets:
Cash equivalents:	0	0
Recurring \| Level III \| Commercial paper
Financial Assets:
Cash equivalents:	$ 0	$ 0

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), classified as current.

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Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Excludes cash and cash equivalents within disposal group and discontinued operation.

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Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

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