Interest expense, net (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Jan. 31, 2015	Jan. 31, 2014
Interest expense, net [Abstract]
Interest expense	$ 1,372us-gaap_InterestExpense	$ 1,855us-gaap_InterestExpense
Interest income	(529)us-gaap_InterestIncomeOther	(544)us-gaap_InterestIncomeOther
Interest expense, net	$ 843us-gaap_InterestIncomeExpenseNet	$ 1,311us-gaap_InterestIncomeExpenseNet

Amount of the cost of borrowed funds accounted for as interest expense.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 20

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6450988&loc=d3e26243-108391

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 225

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-04.9)

-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph 9

-Article 9

Name:	us-gaap_InterestExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration