Stock-based compensation (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended	6 Months Ended
Jan. 31, 2016	Jul. 31, 2016
Option activity [Line Items]
Granted		22
Weighted average grant date fair value		$ 7.33
Unrecognized compensation expense		$ 300
Unrecognized compensation expense recognized period		2 years 3 months 30 days
Restricted Stock [Member]
Option activity [Line Items]
Unrecognized compensation expense		$ 800
Unrecognized compensation expense recognized period		2 years 10 months 30 days
Stock Option [Member]
Option activity [Line Items]
Outstanding at beginning of year	720
Weighted Average Exercise Price Per Share	$ 11.38
Weighted Average Remaining Contractual Term	5 years 1 month 4 days
Options Outstanding Aggregate Intrinsic Value	$ 34	$ 259
Granted		22
Weighted average grant date fair value		$ 7.33
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period		(28)
Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price		$ 6.50
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value		$ 26
Expired or forfeited		(110)
Expired or Forfeited Weighted Average Exercise Price Per Share		$ 10.42
Outstanding end of period		604
Outstanding Weighted Average Exercise Price Per Share		$ 11.63
Outstanding Weighted Average Remaining Contractual Term		4 years 10 months 30 days
Exercisable end of period		511
Exercisable Weighted Average Exercise Price Per Share		$ 12.05
Exercisable Weighted Average Remaining Contractual Term		4 years 3 months 8 days
Exercisable Aggregate Intrinsic Value		$ 220
unvested option [Member]
Option activity [Line Items]
Outstanding at beginning of year	166	93
Weighted Average Exercise Price Per Share	$ 9.51	$ 9.33
Options Outstanding Aggregate Intrinsic Value	$ 0	$ 39
Vested		(60)
Expired or forfeited		(35)
Expired or Forfeited Weighted Average Exercise Price Per Share		$ 8.99

Unrecognized cost of unvested share-based compensation awards.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
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Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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For presentations that combine terminations, 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 or that expired.

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

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

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Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

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

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

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As of the balance sheet date, the number of shares into which fully vested and expected to vest stock options outstanding can be converted under the option plan.

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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

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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

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Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Weighted average remaining contractual term for fully vested and expected to vest options that are exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Weighted average remaining contractual term for fully vested and expected to vest options outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Number of options vested.

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The weighted average price as of the balance sheet date at which grantees could acquire the underlying shares with respect to all outstanding stock options which are in the customized range of exercise prices.

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Number of share options (or share units) exercised during the current period.

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