Note 5 - Investment Securities - Securities in a Continuous Unrealized Loss Position (Details) - USD ($) $ in Thousands	Sep. 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	$ 76,185	$ 116,161
Available for sale securities in a continuous unrealized loss position, less than 12 months, unrealized losses	573	3,173
Available for sale securities in a continuous unrealized loss position, 12 months or more, fair value	8,199
Available for sale securities in a continuous unrealized loss position, 12 months or more, unrealized losses	67
Available for sale securities in a continuous unrealized loss position, fair value	84,384	116,161
Available for sale securities in a continuous unrealized loss position, unrealized losses	640	3,173
Held to maturity securities in a continuous unrealized loss position, less than 12 months, fair value	26,469	68,888
Held to maturity securities in a continuous unrealized loss position, less than 12 months, unrealized losses	219	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	26,469	84,844
Held to maturity securities in a continuous unrealized loss position, unrealized losses	219	780
US Government Agencies Debt Securities [Member]
Held to maturity securities in a continuous unrealized loss position, less than 12 months, fair value	7,067	11,954
Held to maturity securities in a continuous unrealized loss position, less than 12 months, unrealized losses	47	72
Held to maturity securities in a continuous unrealized loss position, 12 months or more, fair value	3,621
Held to maturity securities in a continuous unrealized loss position, 12 months or more, unrealized losses	11
Held to maturity securities in a continuous unrealized loss position, fair value	10,688	11,954
Held to maturity securities in a continuous unrealized loss position, unrealized losses	58	72
Collateralized Mortgage Backed Securities [Member]
Available for sale securities in a continuous unrealized loss position, less than 12 months, fair value	2,584	2,389
Available for sale securities in a continuous unrealized loss position, less than 12 months, unrealized losses	14	14
Available for sale securities in a continuous unrealized loss position, 12 months or more, fair value	3,432	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	6,016	7,891
Available for sale securities in a continuous unrealized loss position, unrealized losses	19	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
US States and Political Subdivisions Debt Securities [Member]
Available for sale securities in a continuous unrealized loss position, less than 12 months, fair value	486	886
Available for sale securities in a continuous unrealized loss position, less than 12 months, unrealized losses	8	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	486	2,700
Available for sale securities in a continuous unrealized loss position, unrealized losses	8	32
Corporate Debt Securities [Member]
Available for sale securities in a continuous unrealized loss position, less than 12 months, fair value	28,859	9,583
Available for sale securities in a continuous unrealized loss position, less than 12 months, unrealized losses	1,142	258
Available for sale securities in a continuous unrealized loss position, 12 months or more, fair value	10,796	2,952
Available for sale securities in a continuous unrealized loss position, 12 months or more, unrealized losses	199	42
Available for sale securities in a continuous unrealized loss position, fair value	39,655	12,535
Available for sale securities in a continuous unrealized loss position, unrealized losses	1,341	300
Asset-backed Securities [Member]
Available for sale securities in a continuous unrealized loss position, less than 12 months, fair value		17,005
Available for sale securities in a continuous unrealized loss position, less than 12 months, unrealized losses		626
Available for sale securities in a continuous unrealized loss position, 12 months or more, fair value	15,717
Available for sale securities in a continuous unrealized loss position, 12 months or more, unrealized losses	466
Available for sale securities in a continuous unrealized loss position, fair value	15,717	17,005
Available for sale securities in a continuous unrealized loss position, unrealized losses	466	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	1,691	1,883
Available for sale securities in a continuous unrealized loss position, 12 months or more, unrealized losses	1,372	1,187
Available for sale securities in a continuous unrealized loss position, fair value	1,691	1,883
Available for sale securities in a continuous unrealized loss position, unrealized losses	1,372	1,187
Available for sale securities in a continuous unrealized loss position, less than 12 months, fair value	108,114	146,024
Available for sale securities in a continuous unrealized loss position, less than 12 months, unrealized losses	1,737	4,086
Available for sale securities in a continuous unrealized loss position, 12 months or more, fair value	39,835	12,151
Available for sale securities in a continuous unrealized loss position, 12 months or more, unrealized losses	2,109	1,310
Available for sale securities in a continuous unrealized loss position, fair value	147,949	158,175
Available for sale securities in a continuous unrealized loss position, unrealized losses	3,846	5,396
Held to maturity securities in a continuous unrealized loss position, less than 12 months, fair value	33,536	88,553
Held to maturity securities in a continuous unrealized loss position, less than 12 months, unrealized losses	266	825
Held to maturity securities in a continuous unrealized loss position, 12 months or more, fair value	3,621	15,956
Held to maturity securities in a continuous unrealized loss position, 12 months or more, unrealized losses	11	48
Held to maturity securities in a continuous unrealized loss position, fair value	37,157	104,509
Held to maturity securities in a continuous unrealized loss position, unrealized losses	$ 277	$ 873