Stock options Option activity (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
Jan. 31, 2015	Jan. 31, 2014	Jan. 31, 2013
Share-based compensation
Number of additional shares authorized	400,000
Initial number of options to grant under plan	350,000
Share-based Payment Award, Options, Grants in Period, Net of Forfeitures	97,000
Stock Option [Member]
Share-based compensation
Options, vested and expected to vest, outstanding, number	764,000	776,000	969,000
Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	$ 11.45	$ 11.69	$ 10.77
Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Remaining Contractual Term	5 years 8 months 6 days	6 years 1 month 6 days	6 years 6 months 24 days
Share-based Payment Award, Options, Outstanding, Intrinsic Value	$ 0	$ 3,859	$ 40
Share-based Payment Award, Options, Exercisable, Number	532,000	513,000
Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price	$ 12.04	$ 13.43
Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term	4 years 6 months 6 days	4 years 9 months 6 days
Share-based Payment Award, Options, Exercisable, Intrinsic Value	0	2,226
Share-based Payment Award, Options, Grants in Period, Net of Forfeitures		103,000
Shares issued	(45,000)	(223,000)
Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price	$ 7.27	$ 7.11
Share-based Payment Award, Options, Exercises in Period, Total Intrinsic Value	194	1,082
Share-based Payment Award, Options, Forfeitures and Expirations in Period	(64,000)	(73,000)
Share-based Payment Award, Options, Forfeitures and Expirations in Period, Weighted Average Exercise Price	$ 18.92	$ 11.90
unvested option [Member]
Share-based compensation
Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	$ 10.11	$ 6.91
Share-based Payment Award, Options, Outstanding, Intrinsic Value	$ 0	$ 4
Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price	$ 12.41	$ 10.55

Initial number of options to grant under plan

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- Definition

Number of additional shares authorized for issuance under an established share-based compensation plan.

+ References

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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.

+ References

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

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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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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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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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- Definition

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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- Definition

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

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- Definition

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

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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 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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- Definition

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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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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