REVENUE, DEFERRED REVENUE AND DEFERRED COMMISSIONS - ASC 606 Impact on Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Jan. 31, 2018	Jan. 31, 2017		Jan. 31, 2018	Jan. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net loss	$ (62,631)	$ (76,369)	[1]	$ (124,118)	$ (216,671)
Adjustments to reconcile net loss to net cash provided by operating activities:
Deferred commission				(26,101)	(8,071)
Accrued expenses and other liabilities				2,415	1,677
Deferred revenue				$ 108,944	79,372
Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net loss		(76,369)			(216,671)
Adjustments to reconcile net loss to net cash provided by operating activities:
Deferred commission					8,071
Accrued expenses and other liabilities					1,677
Deferred revenue					79,372
Accounting Standards Update 2014-09 | Scenario, Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net loss		(93,212)			(255,381)
Adjustments to reconcile net loss to net cash provided by operating activities:
Deferred commission					8,049
Accrued expenses and other liabilities					1,594
Deferred revenue					118,143
Accounting Standards Update 2014-09 | Restatement Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net loss		$ 16,843			38,710
Adjustments to reconcile net loss to net cash provided by operating activities:
Deferred commission					22
Accrued expenses and other liabilities					83
Deferred revenue					$ (38,771)

[1] See Note 3 for a summary of adjustments related to the adoption of the new revenue recognition standard.