Marketable Securities (Details 2) - USD ($) $ in Thousands	Oct. 31, 2015	Jul. 31, 2015
Schedule Of Available For Sale Securities [Line Items]
Unrealized Losses	$ 86	$ 587
Fair Value	7,527	13,284
Federal Home Loan Mortgage Corp. bonds [Member]
Schedule Of Available For Sale Securities [Line Items]
Unrealized Losses	2
Fair Value	1,698
Mutual funds [Member]
Schedule Of Available For Sale Securities [Line Items]
Unrealized Losses	82	18
Fair Value	4,943	4,982
Corporate bonds [Member]
Schedule Of Available For Sale Securities [Line Items]
Unrealized Losses	2
Fair Value	886
Certificates Of Deposit [Member]
Schedule Of Available For Sale Securities [Line Items]
Unrealized Losses		2
Fair Value		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	0	3
Fair Value	$ 0	$ 3,466