Fair Value Measurements (Details) - USD ($) $ in Thousands		Oct. 31, 2018	Jul. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities		$ 2,237	$ 5,612
Equity securities included in other current assets		292	360
Equity securities included in equity investments		2,816
Total		5,345	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]	1,695	1,692
Equity securities included in other current assets	[1]	292	360
Equity securities included in equity investments	[1]
Total	[1]	1,987	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]	542	3,920
Equity securities included in other current assets	[2]
Equity securities included in equity investments	[2]
Total	[2]	542	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]	2,816
Total	[3]	$ 2,816

[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