Note 4 - Investment Securities - Securities in a Continuous Loss Position (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Securities in a continuous loss position, less than 12 months, fair value		$ 109,107
Securities in a continuous loss position, less than 12 months, unrealized losses		716
Securities in a continuous loss position, greater than 12 months, fair value		2,707
Securities in a continuous loss position, greater than 12 months, unrealized losses		28
Securities in a continuous loss position, fair value		111,814
Securities in a continuous loss position, unrealized losses		744
Securities in a continuous loss position, less than 12 months, fair value	$ 153,888
Securities in a continuous loss position, less than 12 months, unrealized losses	4,926
Securities in a continuous loss position, greater than 12 months, fair value	0
Securities in a continuous loss position, greater than 12 months, unrealized losses	0
Securities in a continuous loss position, fair value	153,888
Securities in a continuous loss position, unrealized losses	4,926
US Treasury and Government [Member]
Securities in a continuous loss position, less than 12 months, fair value	1,969	46,805
Securities in a continuous loss position, less than 12 months, unrealized losses	31	117
Securities in a continuous loss position, greater than 12 months, fair value	0	0
Securities in a continuous loss position, greater than 12 months, unrealized losses	0	0
Securities in a continuous loss position, fair value	1,969	46,805
Securities in a continuous loss position, unrealized losses	31	117
US States and Political Subdivisions Debt Securities [Member]
Securities in a continuous loss position, less than 12 months, fair value		4,741
Securities in a continuous loss position, less than 12 months, unrealized losses		32
Securities in a continuous loss position, greater than 12 months, fair value		2,707
Securities in a continuous loss position, greater than 12 months, unrealized losses		28
Securities in a continuous loss position, fair value		7,448
Securities in a continuous loss position, unrealized losses		60
Securities in a continuous loss position, less than 12 months, fair value	73,194
Securities in a continuous loss position, less than 12 months, unrealized losses	3,472
Securities in a continuous loss position, greater than 12 months, fair value	0
Securities in a continuous loss position, greater than 12 months, unrealized losses	0
Securities in a continuous loss position, fair value	73,194
Securities in a continuous loss position, unrealized losses	3,472
Collateralized Mortgage Backed Securities [Member]
Securities in a continuous loss position, less than 12 months, fair value	78,725	57,561
Securities in a continuous loss position, less than 12 months, unrealized losses	1,423	567
Securities in a continuous loss position, greater than 12 months, fair value	0	0
Securities in a continuous loss position, greater than 12 months, unrealized losses	0	0
Securities in a continuous loss position, fair value	78,725	57,561
Securities in a continuous loss position, unrealized losses	$ 1,423	$ 567