INCOME TAXES - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Jul. 31, 2019	Jul. 31, 2018
New Accounting Pronouncement, Early Adoption [Line Items]
Federal statutory income tax rate	21.00%
Valuation allowance for deferred tax assets	$ 509,764	$ 226,987
Valuation allowance increase	(282,800)	$ 65,800
Unrecognized tax benefits that would impact effective tax rate	14,500
Cash and cash equivalents in foreign subsidiaries	218,000
Accounts payable and accrued liabilities	1,300
United States of America, Dollars
New Accounting Pronouncement, Early Adoption [Line Items]
Cash and cash equivalents in foreign subsidiaries	182,600
Federal
New Accounting Pronouncement, Early Adoption [Line Items]
Net operating loss carryforwards	1,400,000
Federal | Research Credit Carryforwards
New Accounting Pronouncement, Early Adoption [Line Items]
Research credit carryforwards	75,800
State
New Accounting Pronouncement, Early Adoption [Line Items]
Net operating loss carryforwards	764,300
State | Research Credit Carryforwards
New Accounting Pronouncement, Early Adoption [Line Items]
Research credit carryforwards	49,500
Foreign Tax Authority | Research Credit Carryforwards
New Accounting Pronouncement, Early Adoption [Line Items]
Research credit carryforwards	$ 14,100