Note 9 - Long-term Debt (Details Textual) - USD ($) $ in Millions	1 Months Ended
	Mar. 31, 2021	Nov. 30, 2018	Jun. 30, 2022	Dec. 31, 2021
Debt Instrument, Face Amount			$ 175	$ 175
Six Point One Eight Percent Fixed To Floating Rate Subordinated Debentures Due December First Two Thousands Twenty Eight [Member]
Debt Instrument, Face Amount		$ 55
Long-term Debt, Percentage Bearing Fixed Interest, Percentage Rate		6.18%
Banking Regulation, Common Equity Tier One Risk-Based Capital, Actual		$ 25
Six Point One Eight Percent Fixed To Floating Rate Subordinated Debentures Due December First Two Thousands Twenty Eight [Member] | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument, Basis Spread on Variable Rate		3.15%
Four Percent Fixed To Floating Rate Subordinated Debentures Due April First Two Thousand Thirty One [Member]
Debt Instrument, Face Amount	$ 120
Long-term Debt, Percentage Bearing Fixed Interest, Percentage Rate	4.00%
Banking Regulation, Common Equity Tier One Risk-Based Capital, Actual			$ 25
Four Percent Fixed To Floating Rate Subordinated Debentures Due April First Two Thousand Thirty One [Member] | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument, Basis Spread on Variable Rate	3.29%