Product Warranties - Additional Information (Detail)	3 Months Ended
Oct. 31, 2015
Product Warranty Liability [Line Items]
Warranty period for retail customers, years	1 year

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

Name:	us-gaap_ProductWarrantyLiabilityLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration