Marketable Securities - Summary of Marketable Securities (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended		12 Months Ended
	Apr. 30, 2014		Jul. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 12,362		$ 9,684
Gross Unrealized Gains
Gross Unrealized Losses
Fair Value	12,362		9,684
Certificates of Deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	8,400	[1]	8,786	[1]
Gross Unrealized Gains		[1]		[1]
Gross Unrealized Losses		[1]		[1]
Fair Value	8,400	[1]	8,786	[1]
Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	3,962		898
Gross Unrealized Gains
Gross Unrealized Losses
Fair Value	$ 3,962		$ 898

[1] Each of the Company's certificates of deposit has a CUSIP, was purchased in the secondary market through a broker and may be sold in the secondary market.