Marketable Securities (Details 2) - USD ($) $ in Thousands	Apr. 30, 2016	Jul. 31, 2015
Schedule Of Available For Sale Securities [Line Items]
Unrealized Losses	$ 217	$ 587
Fair Value	17,739	13,284
Federal Government Sponsored Enterprise notes [Member]
Schedule Of Available For Sale Securities [Line Items]
Unrealized Losses	3
Fair Value	1,852
Mutual funds [Member]
Schedule Of Available For Sale Securities [Line Items]
Unrealized Losses	102	18
Fair Value	4,990	4,982
Equity [Member]
Schedule Of Available For Sale Securities [Line Items]
Unrealized Losses	109
Fair Value	2,354
Certificates Of Deposit [Member]
Schedule Of Available For Sale Securities [Line Items]
Unrealized Losses	1	2
Fair Value	3,586	2,194
International agency notes [Member]
Schedule Of Available For Sale Securities [Line Items]
Unrealized Losses		1
Fair Value		1,119
Straight Path Communications Inc. common stock [Member]
Schedule Of Available For Sale Securities [Line Items]
Unrealized Losses		563
Fair Value		1,523
Municipal Bonds [Member]
Schedule Of Available For Sale Securities [Line Items]
Unrealized Losses	2	3
Fair Value	$ 4,957	$ 3,466