Investments and Fair Value Measurements - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	Oct. 31, 2013	Jul. 31, 2013
Level 3
Fair value measurements Significant unobservable inputs [Line Items]
Investments in auction rate securities	$ 0	$ 666
Level 1
Fair value measurements Significant unobservable inputs [Line Items]
Other investments securities	7,521	7,000
Level 1 | Discontinued Operations
Fair value measurements Significant unobservable inputs [Line Items]
Other investments securities	$ 3,570	$ 3,407