Retirement plans Cash flows (Details) $ in Thousands	12 Months Ended
	Jan. 31, 2016 USD ($)
Compensation and Retirement Disclosure [Abstract]
Defined Benefit Plans, Estimated Future Employer Contributions in Next Fiscal Year	$ 0
Defined Benefit Plan, Contributions by Plan Participants	0
Defined Benefit Plan, Expected Future Benefit Payments, Next Twelve Months	326
Defined Benefit Plan, Expected Future Benefit Payments, Year Two	349
Defined Benefit Plan, Expected Future Benefit Payments, Year Three	348
Defined Benefit Plan, Expected Future Benefit Payments, Year Four	363
Defined Benefit Plan, Expected Future Benefit Payments, Year Five	363
Defined Benefit Plan, Expected Future Benefit Payments, Five Fiscal Years Thereafter	$ 1,841