Note 4 - Earnings Per Share - Basic and Diluted Net Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2022	Jun. 30, 2021
Net earnings	$ 17,038	$ 5,064	$ 7,880	$ 3,199	$ 22,102	$ 11,080
Undistributed earnings	16,183		7,037		20,391	9,393
Common Class A [Member]
Net earnings	2,793		1,299		3,614	1,822
Less dividends declared	129	129	129	128	258	257
Undistributed earnings	$ 2,664		$ 1,170		$ 3,356	$ 1,565
Class A - basic and diluted (in shares)	2,144		2,145		2,145	2,145
Class A common share - basic and diluted (in dollars per share)	$ 1.30		$ 0.61		$ 1.68	$ 0.85
Common Class B [Member]
Net earnings	$ 14,245		$ 6,581		$ 18,488	$ 9,258
Less dividends declared	726	$ 727	714	$ 716	1,453	1,430
Undistributed earnings	$ 13,519		$ 5,867		$ 17,035	$ 7,828
Class A - basic and diluted (in shares)	10,362		10,237		10,368	10,220
Class A common share - basic and diluted (in dollars per share)	$ 1.37		$ 0.64		$ 1.78	$ 0.91