Note 21 - Regulatory Matters (Details Textual) - USD ($) $ / shares in Units, $ in Millions										12 Months Ended	47 Months Ended
	Mar. 20, 2019	Jan. 17, 2019	Dec. 19, 2018	Oct. 11, 2018	Sep. 19, 2018	Jul. 12, 2018	Jun. 20, 2018	Mar. 21, 2018	Jan. 11, 2018	Dec. 31, 2018	Dec. 31, 2018	Jan. 01, 2019	Dec. 31, 2017	Apr. 19, 2016	Jan. 30, 2015	Dec. 31, 2009
Capital Conservation Buffer										2.50%	2.50%
Statutory Accounting Practices, Statutory Amount Available for Dividend Payments without Regulatory Approval										$ 38.8	$ 38.8
Common Stock, Dividends, Per Share, Declared				$ 0.25		$ 0.24			$ 0.22
Common Stock, Dividends, Per Share, Cash Paid			$ 0.25		$ 0.24		$ 0.22	$ 0.22
Stock Repurchase Program, Authorized Amount															$ 20.0
Stock Repurchase Program Additional Authorized Amount														$ 15.0
Stock Repurchased During Period, Shares										199,905	1,156,324
Stock Repurchased During Period, Value										$ 5.9	$ 25.4
Treasury Stock Acquired, Average Cost Per Share										$ 29.73	$ 22
Preferred Securities of Subsidiary Trust										$ 44.1	$ 44.1		$ 43.4
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													$ 43.4
Scenario, Forecast [Member]
Common Stock, Dividends, Per Share, Cash Paid	$ 0.26
Special Dividend [Member]
Common Stock, Dividends, Per Share, Declared				$ 0.75
Common Stock, Dividends, Per Share, Cash Paid			$ 0.75
Subsequent Event [Member]
Common Equity Tier 1 Risk Based Capital Required For Capital Adequacy to Risk Weighted Assets												7.00%
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets												8.50%
Capital Required for Capital Adequacy to Risk Weighted Assets												10.50%
Common Stock, Dividends, Per Share, Declared		$ 0.26