Note 15 - Financial Derivatives (Details Textual) - USD ($)		3 Months Ended		9 Months Ended
	May 31, 2014	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Junior Subordinated Notes	$ 119,100,000
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax		$ 157,000	$ 804,000	$ (94,000)	$ (3,598,000)
Cash [Member]
Collateral Already Posted, Aggregate Fair Value		6,300,000		6,300,000
Interest Rate Swap [Member] | Cash Flow Hedging [Member] | Designated as Hedging Instrument [Member]
Derivative Outstanding, Notional Amount	$ 119,100,000	119,100,000		119,100,000
Derivative Original Maturity	10 years
Derivative, Average Fixed Interest Rate	2.61%
Derivative, Average Variable Interest Rate	1.32%
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax				(2,300,000)
Interest Rate Swap [Member] | Cash Flow Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Expense [Member]
Net Accrued on Interest Rate Swaps		407,000	588,000	1,300,000	1,800,000
Interest Rate Swap [Member] | Fair Value Hedging [Member] | Designated as Hedging Instrument [Member]
Derivative Outstanding, Notional Amount		$ 510,600,000		$ 510,600,000
Derivative, Average Fixed Interest Rate		4.55%		4.55%
Derivative, Average Variable Interest Rate		4.16%		4.16%
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax				$ 1,900,000
Net Accrued on Interest Rate Swaps		$ 514,000	$ 879,000	$ 1,900,000	$ 2,800,000
Derivative, Average Basis Spread on Variable Rate		2.93%		2.93%
Interest Rate Swap [Member] | Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Minimum [Member]
Derivative Original Maturity				4 years
Interest Rate Swap [Member] | Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Maximum [Member]
Derivative Original Maturity				8 years
Negative Fair Value [Member]
Notional Amount Of Option Contract		$ 12,300,000		$ 12,300,000		$ 12,100,000
Open Option Contracts Fair Value		234,000		234,000		121,000
Sum Of Spot And Forward Contract Notional Amount		86,600,000		86,600,000		89,500,000
Negative Fair Value		1,100,000		1,100,000		3,100,000
Positive Fair Value [Member]
Sum Of Spot And Forward Contract Notional Amount		69,300,000		69,300,000		82,400,000
Positive Fair Value		$ 1,700,000		$ 1,700,000		$ 1,300,000