Stock-based compensation (Details) (USD $) Share data in Thousands, except Per Share data, unless otherwise specified	9 Months Ended	12 Months Ended
	Oct. 31, 2014	Jan. 31, 2014
Option activity [Line Items]
Granted	97
Granted, Weighted Average Exercise Price	$ 12.41
Unrecognized compensation expense	$ 900,000
Unrecognized compensation expense recognized period	2 years 6 months 40 days
Restricted Stock [Member]
Option activity [Line Items]
Unrecognized compensation expense	500,000
Unrecognized compensation expense recognized period	2 years 0 months 0 days
Stock Option [Member]
Option activity [Line Items]
Outstanding at beginning of year		776
Weighted Average Exercise Price Per Share		$ 11.69
Weighted Average Remaining Contractual Term		6 years 1 month 24 days
Options Outstanding Aggregate Intrinsic Value	857,000	3,859,000
Granted	97
Granted, Weighted Average Exercise Price	$ 12.41
Exercised	(45)
Exercised Weighted Average Exercise Price Per Share	$ 7.27
Exercised Aggregate Intrinsic Value	155,000
Expired or forfeited	(61)
Expired or Forfeited Weighted Average Exercise Price Per Share	$ 19.35
Outstanding end of period	767
Outstanding Weighted Average Exercise Price Per Share	$ 11.45
Outstanding Weighted Average Remaining Contractual Term	6 years 0 months 0 days
Exercisable end of period	520
Exercisable Weighted Average Exercise Price Per Share	$ 12.09
Exercisable Weighted Average Remaining Contractual Term	4 years 8 months 0 days
Exercisable Aggregate Intrinsic Value	676,000
unvested option [Member]
Option activity [Line Items]
Outstanding at beginning of year	247	263
Weighted Average Exercise Price Per Share	$ 10.10	$ 8.31
Options Outstanding Aggregate Intrinsic Value	$ 180,000	$ 1,633,000
Vested	(102)
Expired or forfeited	(11)
Expired or Forfeited Weighted Average Exercise Price Per Share	$ 8.36