Contingent Liabilities and Commitments - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	1 Months Ended
Jun. 01, 2012	Apr. 30, 2013	Jul. 31, 2012
Loss Contingencies [Line Items]
Repurchase and guarantee reserve balances		$ 4,322	$ 3,150
Chassis delivered to customers in days		90 days
Chassis consigned inventory		10,466
Additional chassis provided by customers		6,295
Payment of obligation	$ 4,700

The amount of cash paid for the settlement of litigation or for other legal issues during the period.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 25

-Subparagraph (g)

-URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3536-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 27

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Name:	us-gaap_PaymentsForLegalSettlements
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration