Other accrued liabilities (Details) $ in Millions	6 Months Ended
Jul. 31, 2016 USD ($)
Other accrued liabilities [Abstract]
Litigation Settlement, Amount	$ 0.8

Amount of judgment or settlement awarded to (against) the entity in respect of litigation.

No definition available.

Name:	us-gaap_LitigationSettlementAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration