Significant accounting policies Net loss per share (Details) - shares shares in Thousands	12 Months Ended
	Jan. 31, 2018	Jan. 31, 2017
Basic weighted average number of common shares outstanding [Line Items]
Basic weighted average number of common shares outstanding	7,680	7,488
Dilutive effect of stock options, deferred stock and restricted stock units	0	0
Stock Option [Member]
Basic weighted average number of common shares outstanding [Line Items]
Stock options not included in the computation of diluted EPS of common stock because the option exercise prices exceeded the average market prices	139	306
Canceled options during the year	(131)	(159)
Stock options with an exercise price below the average stock price	219	218