Note 16 - Financial Derivatives (Details Textual) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended		12 Months Ended
	May 31, 2014	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Junior Subordinated Notes, Total	$ 119,100
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax		$ (2,102)	$ 736	$ (3,326)	$ 2,929
Cash [Member]
Collateral Already Posted, Aggregate Fair Value		6,900		6,900		$ 1,800
Interest Rate Swap [Member] | Cash Flow Hedging [Member] | Designated as Hedging Instrument [Member]
Derivative Outstanding, Notional Amount	$ 119,100	119,100		119,100		119,100
Derivative Original Maturity	10 years
Derivative, Average Fixed Interest Rate	2.61%
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax				3,600		241
Net Accrued on Interest Rate Swaps		$ 8	123	$ 37	396
Interest Rate Swap [Member] | Cash Flow Hedging [Member] | Designated as Hedging Instrument [Member] | London Interbank Offered Rate (LIBOR) [Member]
Derivative, Average Variable Interest Rate		2.50%		2.50%
Interest Rate Swap [Member] | Fair Value Hedging [Member] | Designated as Hedging Instrument [Member]
Derivative Outstanding, Notional Amount		$ 570,800		$ 570,800		613,400
Derivative, Average Fixed Interest Rate		4.72%		4.72%
Derivative, Average Variable Interest Rate		5.10%		5.10%
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax				$ 7,300		6,600
Net Accrued on Interest Rate Swaps		$ 534	$ 0	$ 1,100	$ (229)
Interest Rate Swap [Member] | Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Minimum [Member]
Derivative Original Maturity				3 years
Interest Rate Swap [Member] | Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Maximum [Member]
Derivative Original Maturity				10 years
Interest Rate Swap [Member] | Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | London Interbank Offered Rate (LIBOR) [Member]
Derivative, Average Variable Interest Rate		2.62%		2.62%
Negative Fair Value [Member]
Notional Amount Of Option Contract		$ 1,700		$ 1,700		1,200
Open Option Contracts Fair Value		14		14		6
Sum Of Spot And Forward Contract Notional Amount		95,600		95,600		95,000
Negative Fair Value		876		876		1,800
Positive Fair Value [Member]
Sum Of Spot And Forward Contract Notional Amount		109,700		109,700		86,900
Positive Fair Value		$ 638		$ 638		$ 397