Cash dividend and declared dividends - Additional Information (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	6 Months Ended	3 Months Ended
Apr. 30, 2013	Apr. 30, 2012	Apr. 30, 2013 Dividends Paid	Jan. 31, 2013 Dividends Paid	Apr. 30, 2012 Dividends Paid	Jan. 31, 2012 Dividends Paid
Dividends Payable [Line Items]
Dividends paid, per share			$ 0.07	$ 0.10	$ 0.05	$ 0.05
Dividends paid	$ (1,244)	$ (695)	$ (544)	$ (700)	$ (343)	$ (352)

Cash outflow in the form of ordinary dividends to common shareholders, generally out of earnings.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 20

-Subparagraph a

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Financing Activities

-URI http://asc.fasb.org/extlink&oid=6513228

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 18

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 15

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3291-108585

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