Retirement plans Components of net periodic benefit cost (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Jan. 31, 2013	Jan. 31, 2012	Jan. 31, 2011
Components of net periodic benefit cost [Abstract]
Defined Benefit Plan, Service Cost	$ 171	$ 126	$ 126
Defined Benefit Plan, Interest Cost	299	313	313
Defined Benefit Plan, Expected Return on Plan Assets	(444)	(405)
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	50	127
Recognized actuarial loss	173	62
Defined Benefit Plan, Net Periodic Benefit Cost	$ 249	$ 223