Note 2 - Cash, Cash Equivalents and Restricted Cash (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Average Reserve Balances Required to be Maintained with Federal Bank	$ 60	$ 110
Average Excess Balances Maintained With Federal Reserve Bank	874,800	199,000
Margin Deposit Assets	34,700	17,700
Restricted Cash, Total	9,300	18,900
Bank [Member]
Margin Deposit Assets	$ 11,900	$ 7,100