Fair Value of Anrad Pension Assets by Assets Category (Detail) (USD $) In Thousands, unless otherwise specified	Jul. 31, 2012		Jul. 31, 2011		Jul. 31, 2010
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Fair value of pension assets	$ 10,855		$ 10,536		$ 7,965
Mutual Funds
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Fair value of pension assets	10,855	[1]	10,536	[1]
Fair Value, Inputs, Level 3
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Fair value of pension assets	10,855		10,536
Fair Value, Inputs, Level 3 | Mutual Funds
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Fair value of pension assets	$ 10,855	[1]	$ 10,536	[1]

[1] - This comprises units of segregated pooled funds with an insurance company. These funds have underlying values primarily derived from mutual funds that have debt and equity securities, which are traded on an active market based on the closing price of each trading day.