Note 8 - Treasury Shares (Details Textual) - USD ($) $ / shares in Units, $ in Thousands			3 Months Ended		6 Months Ended	12 Months Ended	114 Months Ended
	Dec. 12, 2018	Aug. 01, 2018	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021	Dec. 31, 2016	Jun. 30, 2021	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)	50,000	100,000			0		1,314,694
Treasury Stock Acquired, Average Cost Per Share (in dollars per share)							$ 4.85
Treasury Stock, Value, Acquired, Cost Method			$ (0)	$ 19			$ 6,400