Financial Assets and Liabilities Measured at Fair Value and Related Valuation Inputs (Parenthetical) (Detail) (USD $) In Thousands, unless otherwise specified	Oct. 31, 2013		Jul. 31, 2013
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, Fair Value Disclosure	$ 117,985		$ 121,541
Cash and Cash Equivalents
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, Fair Value Disclosure	30,716	[1]	28,235	[1]
Cash and Cash Equivalents | Cash held in operating accounts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, Fair Value Disclosure	25,300		25,900
Marketable securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, Fair Value Disclosure	87,269	[2]	93,306	[2]
Marketable securities | Commercial paper which is held to maturity
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, Fair Value Disclosure	$ 0		$ 2,800

[1] Cash and cash equivalents as of October 31, 2013 and July 31, 2013 included cash held in operating accounts of approximately $25.3 million and $25.9 million, respectively that were not subject to fair value measurements. For purposes of this disclosure they are included as having Level 1 inputs.

[2] Marketable securities as of October 31, 2013 and July 31, 2013 excluded approximately $0 million and $2.8 million, respectively, of commercial paper which was held-to-maturity and not subject to fair value measurements.