Stockholder's Equity (Details 2) - Stock Options - $ / shares	12 Months Ended
	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2018
Number Of Shares [Roll Forward]
Non-vested shares at July 31,	4,209,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross	1,175,000
Vested (in shares)	(1,874,000)
Forfeitures or expirations (in shares)	(207,000)
Non-vested shares at July 31,	3,303,000	4,209,000
Weighted Average Grant Date Fair Value [Roll Forward]
Non-vested shares at July 31, fair value	$ 11.05
Grants of non-vested shares, fair value	21.54	$ 15.47	$ 8.88
Vested, fair value	9.98
Forfeitures or expirations, fair value	7.82
Non-vested shares at July 31, fair value	17.58	$ 11.05
Valuation Technique, Option Pricing Model [Member]
Weighted Average Grant Date Fair Value [Roll Forward]
Grants of non-vested shares, fair value	$ 24.89