Significant accounting policies Net income (loss) per share (Details) - shares shares in Thousands	12 Months Ended
	Jan. 31, 2017	Jan. 31, 2016
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Basic	7,488	7,280
Weighted Average Number Diluted Shares Outstanding Adjustment	0	91
Diluted	7,488	7,371
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	306	710
Incremental Common Shares Attributable to Share-based Payment Arrangements	218	10
Stock Option [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Options, Forfeitures and Expirations in Period	(159)	(77)