Note 1 - Significant Accounting Policies (Details Textual) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017 USD ($) shares	Sep. 30, 2016 shares	Sep. 30, 2017 USD ($) shares	Sep. 30, 2016 shares	Dec. 31, 2016 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, Mortgage | $	$ 4.1		$ 4.1		$ 1.0
Servicing Asset | $	$ 611.0		$ 611.0
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	220,000	148,000	220,000	148,000
Employee Stock Option [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	7,000	4,000	7,000	4,000
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements	28,000	79,000	28,000	79,000