Debt Securities (Details 2) - USD ($) $ in Thousands	Oct. 31, 2018	Jul. 31, 2018
Schedule of Available-for-sale Securities [Line Items]
Unrealized Losses	$ 3
Fair Value	2,237
U.S. Treasury notes [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized Losses	2	$ 1
Fair Value	1,695	$ 1,692
Municipal bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized Losses	1
Fair Value	$ 542