Fair Value Measurements (Details) - USD ($)
$ in Thousands
Apr. 30, 2019
Jul. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt securities $ 301 $ 5,612
Equity securities included in other current assets 523 360
Equity securities included in equity investments 3,344  
Total 4,168 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] 1,692
Equity securities included in other current assets [1] 523 360
Equity securities included in equity investments [1]  
Total [1] 523 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] 301 3,920
Equity securities included in other current assets [2]
Equity securities included in equity investments [2]  
Total [2] 301 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 [3]
Equity securities included in other current assets [3]
Equity securities included in equity investments [3] 3,344  
Total [3] $ 3,344
[1] quoted prices in active markets for identical assets or liabilities
[2] observable inputs other than quoted prices in active markets for identical assets and liabilities
[3] no observable pricing inputs in the market