Retirement plans Multi employer (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Jan. 31, 2014	Jan. 31, 2013
Northern Illinois Pension Plan [Member]
Multiemployer Plans [Line Items]
Entity Tax Identification Number	362663798
Multiemployer Plan Number	001
Multiemployer Plans, Certified Zone Status	Green
Multiemployer Plans, Funding Improvement Plan and Rehabilitation Plan	No
Multiemployer Plan, Period Contributions	$ 0	$ 7
Multiemployer Plans, Surcharge	No
Multiemployer Plans, Collective-Bargaining Arrangement, Expiration Date	Jun. 01, 2014
Pipe Fitters Retirement Fund, Local 597 [Member]
Multiemployer Plans [Line Items]
Entity Tax Identification Number	626105084
Multiemployer Plan Number	001
Multiemployer Plans, Certified Zone Status	Green
Multiemployer Plans, Funding Improvement Plan and Rehabilitation Plan	No
Multiemployer Plan, Period Contributions	275	102
Multiemployer Plans, Surcharge	No
Multiemployer Plans, Collective-Bargaining Arrangement, Expiration Date	Jun. 01, 2014
Plumbers & Pipefitters Local 572 Pension Fund [Member]
Multiemployer Plans [Line Items]
Entity Tax Identification Number	626102837
Multiemployer Plan Number	001
Multiemployer Plans, Certified Zone Status	Green
Multiemployer Plans, Funding Improvement Plan and Rehabilitation Plan	No
Multiemployer Plan, Period Contributions	192	250
Multiemployer Plans, Surcharge	No
Multiemployer Plans, Collective-Bargaining Arrangement, Expiration Date	Mar. 31, 2016
Denmark
Multiemployer Plans [Line Items]
Multiemployer Plan, Period Contributions	$ 350	$ 353