Note 1 - Summary of Business and Significant Accounting Policies - Basic and Diluted Net (Loss) Income Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Jan. 31, 2021	Oct. 31, 2020	Jul. 31, 2020	Apr. 30, 2020	Jan. 31, 2020	Oct. 31, 2019	Jul. 31, 2019	Apr. 30, 2019	Jan. 31, 2021	Jan. 31, 2020	Jan. 31, 2019
Net income (loss)	$ 8,202	$ 3,213	$ 60	$ (410)	$ 410	$ 125	$ (13,250)	$ (3,234)	$ 11,065	$ (15,949)	$ 10,428
Less: dividends declared									(5,780)	(5,617)	(5,479)
Undistributed net income (loss)									5,285	(21,566)	4,949
Dividends declared									5,780	5,617	5,479
Allocation of undistributed net income (loss)									5,285	(21,566)	4,949
Common Class A [Member]
Net income (loss)									9,541	(13,692)	8,939
Less: dividends declared									(4,982)	(4,827)	(4,696)
Undistributed net income (loss)									4,559	(18,519)	4,243
Dividends declared									4,982	4,827	4,696
Allocation of undistributed net income (loss)									$ 4,559	$ (18,519)	$ 4,243
Weighted average shares of common stock outstanding—basic (in shares)									17,274	16,709	16,267
Weighted average potential shares of common stock (in shares)									748	0	1,585
Weighted average shares of common stock and potential common shares outstanding—diluted (in shares)									18,022	16,709	17,852
Basic net (loss) income per common share (in dollars per share)	$ 0.41	$ 0.16	$ 0.00	$ (0.02)	$ 0.02	$ 0.01	$ (0.69)	$ (0.17)	$ 0.55	$ (0.82)	$ 0.55
Diluted net (loss) income per common share (in dollars per share)	0.39	0.16	0.00	(0.02)	0.02	0.01	(0.69)	(0.17)	$ 0.53	$ (0.82)	$ 0.50
Common Class B [Member]
Net income (loss)									$ 1,524	$ (2,257)	$ 1,489
Less: dividends declared									(798)	(790)	(783)
Undistributed net income (loss)									726	(3,047)	706
Dividends declared									798	790	783
Allocation of undistributed net income (loss)									$ 726	$ (3,047)	$ 706
Weighted average shares of common stock outstanding—basic (in shares)									3,326	3,289	3,256
Weighted average potential shares of common stock (in shares)									67	0	166
Weighted average shares of common stock and potential common shares outstanding—diluted (in shares)									3,393	3,289	3,422
Basic net (loss) income per common share (in dollars per share)	0.34	0.13	0.00	(0.02)	0.02	0.01	(0.57)	(0.14)	$ 0.46	$ (0.69)	$ 0.46
Diluted net (loss) income per common share (in dollars per share)	$ 0.33	$ 0.13	$ 0.00	$ (0.02)	$ 0.02	$ 0.01	$ (0.57)	$ (0.14)	$ 0.45	$ (0.69)	$ 0.44