Note 5 - Investment Securities - Securities in a Continuous Unrealized Loss Position (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Collateralized Mortgage Obligations [Member]
Available for sale securities in a continuous unrealized loss position, less than 12 months, fair value	$ 11,320	$ 116,161
Available for sale securities in a continuous unrealized loss position, less than 12 months, unrealized losses	93	3,173
Available for sale securities in a continuous unrealized loss position, 12 months or more, fair value	9,728
Available for sale securities in a continuous unrealized loss position, 12 months or more, unrealized losses	41
Available for sale securities in a continuous unrealized loss position, fair value	21,048	116,161
Available for sale securities in a continuous unrealized loss position, unrealized losses	134	3,173
Held to maturity securities in a continuous unrealized loss position, less than 12 months, fair value	20,383	68,888
Held to maturity securities in a continuous unrealized loss position, less than 12 months, unrealized losses	114	732
Held to maturity securities in a continuous unrealized loss position, 12 months or more, fair value		15,956
Held to maturity securities in a continuous unrealized loss position, 12 months or more, unrealized losses		48
Held to maturity securities in a continuous unrealized loss position, fair value	20,383	84,844
Held to maturity securities in a continuous unrealized loss position, unrealized losses	114	780
US Government Agencies Debt Securities [Member]
Held to maturity securities in a continuous unrealized loss position, less than 12 months, fair value		11,954
Held to maturity securities in a continuous unrealized loss position, less than 12 months, unrealized losses		72
Held to maturity securities in a continuous unrealized loss position, 12 months or more, fair value	3,798
Held to maturity securities in a continuous unrealized loss position, 12 months or more, unrealized losses	10
Held to maturity securities in a continuous unrealized loss position, fair value	3,798	11,954
Held to maturity securities in a continuous unrealized loss position, unrealized losses	10	72
Collateralized Mortgage Backed Securities [Member]
Available for sale securities in a continuous unrealized loss position, less than 12 months, fair value		2,389
Available for sale securities in a continuous unrealized loss position, less than 12 months, unrealized losses		14
Available for sale securities in a continuous unrealized loss position, 12 months or more, fair value	3,604	5,502
Available for sale securities in a continuous unrealized loss position, 12 months or more, unrealized losses	5	64
Available for sale securities in a continuous unrealized loss position, fair value	3,604	7,891
Available for sale securities in a continuous unrealized loss position, unrealized losses	5	78
Held to maturity securities in a continuous unrealized loss position, less than 12 months, fair value		7,711
Held to maturity securities in a continuous unrealized loss position, less than 12 months, unrealized losses		21
Held to maturity securities in a continuous unrealized loss position, 12 months or more, fair value
Held to maturity securities in a continuous unrealized loss position, 12 months or more, unrealized losses
Held to maturity securities in a continuous unrealized loss position, fair value		7,711
Held to maturity securities in a continuous unrealized loss position, unrealized losses		21
Corporate Debt Securities [Member]
Available for sale securities in a continuous unrealized loss position, less than 12 months, fair value	33,682	9,583
Available for sale securities in a continuous unrealized loss position, less than 12 months, unrealized losses	1,318	258
Available for sale securities in a continuous unrealized loss position, 12 months or more, fair value	5,804	2,952
Available for sale securities in a continuous unrealized loss position, 12 months or more, unrealized losses	191	42
Available for sale securities in a continuous unrealized loss position, fair value	39,486	12,535
Available for sale securities in a continuous unrealized loss position, unrealized losses	1,509	300
US States and Political Subdivisions Debt Securities [Member]
Available for sale securities in a continuous unrealized loss position, less than 12 months, fair value		886
Available for sale securities in a continuous unrealized loss position, less than 12 months, unrealized losses		15
Available for sale securities in a continuous unrealized loss position, 12 months or more, fair value		1,814
Available for sale securities in a continuous unrealized loss position, 12 months or more, unrealized losses		17
Available for sale securities in a continuous unrealized loss position, fair value		2,700
Available for sale securities in a continuous unrealized loss position, unrealized losses		32
Asset-backed Securities [Member]
Available for sale securities in a continuous unrealized loss position, less than 12 months, fair value	6,463	17,005
Available for sale securities in a continuous unrealized loss position, less than 12 months, unrealized losses	491	626
Available for sale securities in a continuous unrealized loss position, 12 months or more, fair value	9,600
Available for sale securities in a continuous unrealized loss position, 12 months or more, unrealized losses	271
Available for sale securities in a continuous unrealized loss position, fair value	16,063	17,005
Available for sale securities in a continuous unrealized loss position, unrealized losses	762	626
Collateralized Debt Obligations [Member]
Available for sale securities in a continuous unrealized loss position, less than 12 months, fair value
Available for sale securities in a continuous unrealized loss position, less than 12 months, unrealized losses
Available for sale securities in a continuous unrealized loss position, 12 months or more, fair value	1,755	1,883
Available for sale securities in a continuous unrealized loss position, 12 months or more, unrealized losses	1,310	1,187
Available for sale securities in a continuous unrealized loss position, fair value	1,755	1,883
Available for sale securities in a continuous unrealized loss position, unrealized losses	1,310	1,187
Available for sale securities in a continuous unrealized loss position, less than 12 months, fair value	51,465	146,024
Available for sale securities in a continuous unrealized loss position, less than 12 months, unrealized losses	1,902	4,086
Available for sale securities in a continuous unrealized loss position, 12 months or more, fair value	30,491	12,151
Available for sale securities in a continuous unrealized loss position, 12 months or more, unrealized losses	1,818	1,310
Available for sale securities in a continuous unrealized loss position, fair value	81,956	158,175
Available for sale securities in a continuous unrealized loss position, unrealized losses	3,720	5,396
Held to maturity securities in a continuous unrealized loss position, less than 12 months, fair value	20,383	88,553
Held to maturity securities in a continuous unrealized loss position, less than 12 months, unrealized losses	114	825
Held to maturity securities in a continuous unrealized loss position, 12 months or more, fair value	3,798	15,956
Held to maturity securities in a continuous unrealized loss position, 12 months or more, unrealized losses	10	48
Held to maturity securities in a continuous unrealized loss position, fair value	24,181	104,509
Held to maturity securities in a continuous unrealized loss position, unrealized losses	$ 124	$ 873