Note 12 - Derivative Financial Instruments - Derivative Financial Instruments (Details) - USD ($) $ in Thousands		Sep. 30, 2019	Dec. 31, 2018
Interest rate swaps, notional amount		$ 896,752	$ 745,619
Interest rate swaps, net carrying value	[1]	(30,832)	13,722
Designated as Hedging Instrument [Member]
Interest rate swaps, notional amount		318,900	267,800
Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member]
Interest rate swaps, notional amount		541,500	441,500
Not Designated as Hedging Instrument [Member]
Interest rate swaps, notional amount		36,300	36,300
Interest Rate Swaps 1 [Member] | Designated as Hedging Instrument [Member] | Fair Value Hedging [Member]
Interest rate swaps, notional amount		50,463	248,330
Interest rate swaps, net carrying value	[1]	156	10,593
Interest Rate Swaps 1 [Member] | Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member]
Interest rate swaps, notional amount		0	441,500
Interest rate swaps, net carrying value	[1]	0	5,368
Interest Rate Swaps 2 [Member] | Designated as Hedging Instrument [Member] | Fair Value Hedging [Member]
Interest rate swaps, notional amount		268,468	19,468
Interest rate swaps, net carrying value	[1]	(13,277)	(502)
Interest Rate Swaps 2 [Member] | Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member]
Interest rate swaps, notional amount		541,500	0
Interest rate swaps, net carrying value	[1]	(11,695)	0
Interest Rate Swap [Member]
Interest rate swaps, notional amount		337,300	286,100
Interest Rate Swap [Member] | Not Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member]
Interest rate swaps, notional amount		36,321	36,321
Interest rate swaps, net carrying value	[1]	$ (6,016)	$ (1,737)

[1] Derivatives in a positive position are recorded as "Other assets" and derivatives in a negative position are recorded as "Other liabilities" in the Consolidated Statements of Financial Condition.