Note 21 - Regulatory Matters (Details Textual) - USD ($) $ / shares in Units, $ in Millions									12 Months Ended	35 Months Ended
	Mar. 21, 2018	Jan. 11, 2018	Dec. 20, 2017	Sep. 20, 2017	Jul. 13, 2017	Jun. 21, 2017	Mar. 22, 2017	Jan. 12, 2017	Dec. 31, 2017	Dec. 31, 2017	Jan. 01, 2019	Dec. 31, 2016	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									$ 42.6	$ 42.6
Common Stock, Dividends, Per Share, Declared					$ 0.19			$ 0.18
Common Stock, Dividends, Per Share, Cash Paid			$ 0.19	$ 0.19		$ 0.18	$ 0.18
Stock Repurchase Program, Authorized Amount														$ 20.0
Stock Repurchase Program Additional Authorized Amount													$ 15.0
Stock Repurchased During Period, Shares									0	956,419
Stock Repurchased During Period, Value										$ 19.5
Treasury Stock Acquired, Average Cost Per Share										$ 20.38
Preferred Securities of Subsidiary Trust									$ 43.4	$ 43.4		$ 42.8
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	$ 43.4		$ 42.8
Subsequent Event [Member]
Common Stock, Dividends, Per Share, Declared		$ 0.22
Scenario, Forecast [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, Cash Paid	$ 0.22