Financial Assets and Liabilities Measured at Fair Value and Related Valuation Inputs (Parenthetical) (Detail) (USD $) In Thousands, unless otherwise specified	Jul. 31, 2014		Jul. 31, 2013
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, Fair Value Disclosure	$ 98,928		$ 121,541
Cash and Cash Equivalents
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, Fair Value Disclosure	59,269	[1]	28,235	[1]
Marketable Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, Fair Value Disclosure	39,659		93,306	[2]
Commercial paper which is held to maturity | Marketable Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, Fair Value Disclosure			2,800
Cash held in operating accounts | Cash and Cash Equivalents
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, Fair Value Disclosure	$ 56,000		$ 25,900

[1] Cash and cash equivalents as of July 31, 2014 and July 31, 2013 includes cash held in operating accounts of approximately $56.0 million and $25.9 million, respectively, that are not subject to fair value measurements. For purposes of this disclosure they are included as having Level 1 inputs.

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