Note 1 - Description of Business and Summary of Significant Accounting Policies - Basic and Diluted Net Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Net earnings (loss)	$ 12,795	$ (8,743)
Undistributed earnings (loss)	9,428	(12,095)
Common Class A [Member]
Net earnings (loss)	2,089	(1,531)
Less dividends declared	515	518
Undistributed earnings (loss)	$ 1,574	$ (2,049)
Weighted-average shares outstanding, basic and diluted (in shares)	2,145	2,167
Net earnings per share, basic and diluted (in dollars per share)	$ 0.97	$ (0.71)
Common Class B [Member]
Net earnings (loss)	$ 10,706	$ (7,212)
Less dividends declared	2,852	2,834
Undistributed earnings (loss)	$ 7,854	$ (10,046)
Weighted-average shares outstanding, basic and diluted (in shares)	10,185	10,117
Net earnings per share, basic and diluted (in dollars per share)	$ 1.05	$ (0.71)