Net Income Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Apr. 30, 2021	Apr. 30, 2020
Net income per common share:
Net income	$ 4,641	$ 8,634
Denominator for basic net income per share (weighted-average shares which exclude shares in the treasury, 509,242 at April 30, 2021 and 2020	7,989,215	7,972,423
Effect of dilutive securities from restricted stock plan	154,590	72,426
Denominator for diluted net income per share (adjusted weighted average shares)	8,143,805	8,044,849
Basic net income per share	$ 0.58	$ 1.08
Diluted net income per share	$ 0.57	$ 1.07