Note 8 - Common Stock (Details Textual) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Sep. 16, 2021	Mar. 26, 2018
The 2018 Repurchase Plan [Member]
Stock Repurchase Program, Number of Shares Authorized to be Repurchased (in shares)				500,000
The 2021 Repurchase Plan [Member]
Stock Repurchase Program, Authorized Amount			$ 2.5
Common Class A [Member]
Stock Issued During Period, Shares, New Issues (in shares)	0	0
Common Class C [Member]
Stock Issued During Period, Shares, New Issues (in shares)	0	0
Common Class B [Member]
Stock Issued During Period, Shares, New Issues (in shares)	0	0