Note 4 - Cash, Cash Equivalents and Restricted Cash (Details Textual) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Average Reserve Balances Required to be Maintained with Federal Bank	$ 78	$ 110
Margin Deposit Assets	39,000	17,700
Restricted Cash, Total	21,800	18,900
Bank [Member]
Margin Deposit Assets	$ 13,200	$ 7,100