Stock option plan (Schedule of Stock Option Activity) (Details) - Employee Stock Option [Member] - USD ($)			9 Months Ended
Nov. 10, 2016	Sep. 04, 2014	Jul. 31, 2018
No. of Options Outstanding
Options outstanding beginning of period			$ 267,780
Options granted during period	38,000	246,000	38,000
Options forfeited/cancelled during period
Options outstanding end of period			305,780
Options vested and expected to vest			299,140
Options exercisable at end of period			147,940
Weighted Average Exercise Price
Options outstanding beginning of period			$ 18.81
Options granted during period	$ 21.00	$ 18.45	15.50
Options forfeited/cancelled during period
Options outstanding end of period			$ 18.40

Unrecognized cost of unvested options awarded to employees as compensation.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (i)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

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Weighted average price of options that were either forfeited or expired.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
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- Definition

The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
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- Definition

Gross number of share options (or share units) granted during the period.

+ References

No definition available.

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Number of options outstanding, including both vested and non-vested options.

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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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- Definition

Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

+ References

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-Publisher FASB
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-Topic 718
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- Definition

Number of fully vested and expected to vest exercisable options that may be converted into shares under option plan. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

+ References

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-Publisher FASB
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Number of fully vested and expected to vest options outstanding that can be converted into shares under option plan. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition

Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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