Convertible Senior Notes (Schedule of Interest Expense) (Details) - USD ($) $ in Thousands	12 Months Ended
	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2018
Debt Instrument [Line Items]
Contractual interest expense	$ 17,945	$ 17,334	$ 6,442
Effective interest rate	5.53%
Senior Notes
Debt Instrument [Line Items]
Contractual interest expense	$ 5,000	5,000	1,903
Amortization of debt discount	11,705	11,131	4,134
Amortization of debt issuance costs	1,181	1,063	378
Total	$ 17,886	$ 17,194	$ 6,415