Note 1 - Significant Accounting Policies (Details Textual) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019 USD ($) shares	Jun. 30, 2018 shares	Jun. 30, 2019 USD ($) shares	Jun. 30, 2018 shares	Jan. 01, 2019 USD ($)	Dec. 31, 2018 USD ($)
Number of Unconsolidated Business Trusts Formed to Issue Trust Preferred Securities	5		5
Interest Income on Commercial and Mortgage Loans Discontinued Period			90 days
Maximum Delinquency Period for Consumer and Credit Card Loans to be Charged Off			120 days
Loans Receivable Held-for-sale, Net, Not Part of Disposal Group, Ending Balance	$ 4.5		$ 4.5			$ 1.1
Servicing Asset, Total	$ 629.0		$ 629.0
Accounting Standards Update 2016-02 [Member]
Operating Lease, Right-of-Use Asset					$ 1.3
Operating Lease, Liability, Total					$ 1.3
Core Deposits [Member]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life			10 years
Restricted Stock [Member]
Incremental Common Shares Attributable to Participating Nonvested Shares with Non-forfeitable Dividend Rights | shares	261,000	234,000	261,000	234,000
Share-based Payment Arrangement, Option [Member]
Incremental Common Shares Attributable to Participating Nonvested Shares with Non-forfeitable Dividend Rights | shares	10,000	17,000	10,000	17,000
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount | shares	7,000	7,000	7,000	7,000