Note 20 - Regulatory Matters (Details Textual) - USD ($) $ / shares in Units, $ in Millions											12 Months Ended	60 Months Ended
	Mar. 18, 2020	Jan. 16, 2020	Dec. 18, 2019	Oct. 10, 2019	Sep. 18, 2019	Jul. 11, 2019	Jun. 19, 2019	Apr. 11, 2019	Mar. 20, 2019	Jan. 17, 2019	Dec. 31, 2019	Dec. 31, 2019	May 31, 2019	Dec. 31, 2018	Dec. 31, 2009
Capital Conservation Buffer											2.50%	2.50%
Common Equity Tier 1 Risk Based Capital Required For Capital Adequacy to Risk Weighted Assets											7.00%	7.00%
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets											8.50%	8.50%
Capital Required for Capital Adequacy to Risk Weighted Assets											10.50%	10.50%
Statutory Accounting Practices, Statutory Amount Available for Dividend Payments without Regulatory Approval											$ 75.2	$ 75.2
Common Stock, Dividends, Per Share, Declared				$ 0.27		$ 0.27		$ 0.26		$ 0.26
Stock Repurchase Program, Authorized Amount													$ 20.0
Stock Repurchased During Period, Shares											233,300	1,400,000
Stock Repurchased During Period, Value											$ 7.2	$ 32.6
Treasury Stock Acquired, Average Cost Per Share											$ 30.79	$ 23.47
Preferred Securities of Subsidiary Trust											$ 44.8	$ 44.8		$ 44.1
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											$ 44.8	$ 44.8		$ 44.1
Common Stock, Dividends, Per Share, Cash Paid			$ 0.27		$ 0.27		$ 0.26		$ 0.26
Forecast [Member]
Common Stock, Dividends, Per Share, Cash Paid	$ 0.28
Subsequent Event [Member]
Common Stock, Dividends, Per Share, Declared		$ 0.28