Note 7 - Treasury Shares (Details Textual) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	12 Months Ended	135 Months Ended
	Mar. 31, 2023	Dec. 31, 2016	Mar. 31, 2023	Dec. 31, 2013	Dec. 31, 2012
Stock Repurchase Program, Number of Shares Authorized to be Repurchased (in shares)		1,500,000		1,000,000	500,000
Stock Repurchase Program, Additional Shares Authorized (in shares)		500,000
Treasury Stock, Shares, Acquired (in shares)	0		1,314,694
Treasury Stock Acquired, Average Cost Per Share (in dollars per share)			$ 4.85
Treasury Stock, Value, Acquired, Cost Method			$ 6.4