Note 7 - Investment Securities (Details Textual) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Interest Receivable	$ 56,844		$ 56,844		$ 59,032
Equity Securities, FV-NI, Unrealized Gain (Loss), Total	3	$ 1,600	(3,628)	$ (1,928)
Equity Securities, FV-NI, Current	20,117		20,117		23,744
Debt Securities, Available-for-sale, Restricted	30,900		30,900		$ 22,700
Debt Securities, Available-for-sale [Member]
Interest Receivable	$ 2,600		$ 2,600