Retirement plans Deferred compensation (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
Jan. 31, 2014	Jan. 31, 2013
Deferred compensation [Line Items]
Deferred shares outstanding at January 31, 2014	28,891	0
Deferred Compensation Liability, Current	$ 189	$ 163
Deferred compensation liabilities	6,509	5,670
Deferred Compensation Liability, Current and Noncurrent	6,698	5,833
Deferred compensation expense	$ 519	$ 484

The compensation expense recognized during the period pertaining to the deferred compensation arrangement.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5047-113901

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 710

-SubTopic 10

-Section 30

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6409875&loc=d3e20015-108363

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- Definition

Aggregate carrying value as of the balance sheet date of the liabilities for all deferred compensation arrangements payable beyond one year (or the operating cycle, if longer).

+ References

No definition available.

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- Definition

Aggregate carrying value as of the balance sheet date of the liabilities for all deferred compensation arrangements payable within one year (or the operating cycle, if longer). Represents currently earned compensation under compensation arrangements that is not actually paid until a later date.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 710

-SubTopic 10

-Section 30

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6409875&loc=d3e20028-108363

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 710

-SubTopic 10

-Section 25

-Paragraph 9

-URI http://asc.fasb.org/extlink&oid=6409733&loc=d3e19512-108361

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- Definition

Aggregate carrying value as of the balance sheet date of the liabilities for all deferred compensation arrangements. Represents currently earned compensation under compensation arrangements that is not actually paid until a later date.

+ References

No definition available.

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- Definition

Number of equity instruments other than options outstanding, including both vested and non-vested instruments.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(1)(i)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

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-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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