Retirement plans Deferred compensation (Details) - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2014
Deferred compensation [Line Items]
Deferred Compensation Arrangement with Individual, Common Stock Reserved for Future Issuance	9,991
Deferred shares outstanding		85,554	50,000
Deferred Compensation Liability	$ 6,167	$ 213
Deferred compensation liabilities	495	6,560
Deferred Compensation Liability, Current and Noncurrent	6,662	6,773
Deferred compensation expense	$ 36	$ 270