Note 13 - Regulatory Matters (Details Textual) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions							3 Months Ended		9 Months Ended
	Sep. 14, 2022	Jul. 14, 2022	Jun. 15, 2022	Apr. 14, 2022	Mar. 16, 2022	Jan. 13, 2022	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021	May 31, 2021	Dec. 31, 2009
Preferred Securities of Subsidiary Trust							$ 46.7		$ 46.7		$ 46.2
Maximum Restricted Core Element Allowed in Tier One Capital Percent									25.00%
Maximum Level of Consolidated Aggregate Assets Allowing for Inclusion of Trust Preferred Securities in Tier One Capital													$ 15,000.0
Trust Preferred Securities Included in Tier One Capital							$ 46.7		$ 46.7		$ 46.2
Capital Conservation Buffer							2.50%		2.50%
Common Equity Tier 1 Risk Based Capital Required For Capital Adequacy to Risk Weighted Assets							0.070		0.070
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets							0.085		0.085
Capital Required for Capital Adequacy to Risk Weighted Assets							0.105		0.105
Common Stock, Dividends, Per Share, Declared (in dollars per share)		$ 0.32		$ 0.31		$ 0.31
Common Stock, Dividends, Per Share, Cash Paid (in dollars per share)	$ 0.32		$ 0.31		$ 0.31		$ 0.32	$ 0.30	$ 0.94	$ 0.88
Stock Repurchase Program, Remaining Authorized Repurchase Amount							$ 6.8		$ 6.8
Stock Repurchase Program, Authorized Amount												$ 20.0
Stock Repurchased During Period, Shares (in shares)									0