Retirement plan - Additional Information (Detail) - USD ($)	12 Months Ended
Oct. 31, 2015	Oct. 31, 2014
Compensation And Retirement [Line Items]
Pension and Other Postretirement Benefit Contributions	$ 160,000	$ 152,000
Percentage Of Employee Contribution Paid	3.00%

The increase in the fair value of plan assets from contributions made by the employer.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (b)(3)
-URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920

Name:	us-gaap_DefinedBenefitPlanContributionsByEmployer
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration