Convertible Senior Notes (Schedule of Net Carrying Value) (Details) - USD ($)	Jul. 31, 2020	Jul. 31, 2019
Debt Disclosure [Abstract]
Principal	$ 400,000,000	$ 400,000,000
Less unamortized:
Debt discount	62,508,000	74,213,000
Debt issuance costs	7,284,000	8,465,000
Net carrying amount	$ 330,208,000	$ 317,322,000

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Face (par) amount of debt instrument at time of issuance.

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Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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