Note 4 - Securities in a Continuous Loss Position (Details) - USD ($)	Jun. 30, 2016	Dec. 31, 2015
US States and Political Subdivisions Debt Securities [Member]
Securities in a continuous loss position, less than 12 months, fair value	$ 3,243,000	$ 4,741,000
Securities in a continuous loss position, less than 12 months, unrealized losses	20,000	32,000
Securities in a continuous loss position, greater than 12 months, fair value	255,000	2,707,000
Securities in a continuous loss position, greater than 12 months, unrealized losses	1,000	28,000
Securities in a continuous loss position, fair value	3,498,000	7,448,000
Securities in a continuous loss position, unrealized losses	21,000	60,000
US Treasury and Government [Member]
Securities in a continuous loss position, less than 12 months, fair value		46,805,000
Securities in a continuous loss position, less than 12 months, unrealized losses		117,000
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		46,805,000
Securities in a continuous loss position, unrealized losses		117,000
Collateralized Mortgage Backed Securities [Member]
Securities in a continuous loss position, less than 12 months, fair value	9,143,000	57,561,000
Securities in a continuous loss position, less than 12 months, unrealized losses	26,000	567,000
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	9,143,000	57,561,000
Securities in a continuous loss position, unrealized losses	26,000	567,000
Securities in a continuous loss position, less than 12 months, fair value	12,386,000	109,107,000
Securities in a continuous loss position, less than 12 months, unrealized losses	46,000	716,000
Securities in a continuous loss position, greater than 12 months, fair value	255,000	2,707,000
Securities in a continuous loss position, greater than 12 months, unrealized losses	1,000	28,000
Securities in a continuous loss position, fair value	12,641,000	111,814,000
Securities in a continuous loss position, unrealized losses	$ 47,000	$ 744,000