Note 4 - Cash, Cash Equivalents and Restricted Cash (Details Textual) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2021	Dec. 31, 2020
Average Reserve Balances Required to be Maintained with Federal Bank	$ 0	$ 60
Margin Deposit Assets	34,000	34,700
Restricted Cash, Total	2,800	9,300
Bank [Member]
Margin Deposit Assets	$ 9,100	$ 11,900