Inventories - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	Apr. 30, 2015	Jul. 31, 2014
Inventory [Line Items]
Inventory	$ 286,429us-gaap_InventoryGross	$ 244,342us-gaap_InventoryGross
Subsidiaries valued inventory in first-in, first-out method	$ 55,826us-gaap_FIFOInventoryAmount	$ 36,096us-gaap_FIFOInventoryAmount

Gross amount, as of the balance sheet date, of merchandise, goods, commodities, or supplies held for future sale or to be used in manufacturing, servicing or production process.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.6(a))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Name:	us-gaap_InventoryGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant