Fair Value Measurements (Details) - USD ($) $ in Thousands	Jul. 31, 2019	Jul. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities	$ 2,534	$ 5,612
Equity investments included in current assets	5,688	360
Equity investments included in noncurrent assets	3,619
Total	11,841	5,972
Fair Value Measurements, Recurring basis [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities		1,692
Equity investments included in current assets	5,688	360
Equity investments included in noncurrent assets
Total	5,688	2,052
Fair Value Measurements, Recurring basis [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities	2,534	3,920
Equity investments included in current assets
Equity investments included in noncurrent assets
Total	2,534	3,920
Fair Value Measurements, Recurring basis [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities
Equity investments included in current assets
Equity investments included in noncurrent assets	3,619
Total	$ 3,619