Condensed Consolidating Financial Information - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	Jul. 31, 2014 Guarantor Subsidiaries [Member]	Jul. 31, 2013 2020 Notes [Member]	Jul. 31, 2013 2020 Notes [Member] Domestic Subsidiaries [Member]
Debt Instrument [Line Items]
Notes issued, aggregate principal amount		$ 225,000
Percentage of ownership owned by parent in subsidiaries	100.00%		100.00%