Retirement plans 401K (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Jan. 31, 2013	Jan. 31, 2012
401K [Abstract]
401K employee pretax payroll contributions limit	16.00%
Company matches contribution	50.00%
maximum % of each participant's salary	3.00%
Employer contributions to 401K	$ 560	$ 558