Note 3 - Securities - Available-for-sale Securities (Details) - USD ($)	Dec. 31, 2016	Dec. 31, 2015
Amortized Cost	$ 336,562,000	$ 344,796,000
Gross Unrealized Gains	927,000	4,265,000
Gross Unrealized Losses	(9,429,000)	(2,069,000)
Fair Value	328,060,000	346,992,000
US Government Agencies Debt Securities [Member]
Amortized Cost	159,271,000	146,660,000
Gross Unrealized Gains	106,000	1,932,000
Gross Unrealized Losses	(7,337,000)	(1,552,000)
Fair Value	152,040,000	147,040,000
Collateralized Mortgage Backed Securities [Member]
Amortized Cost	47,329,000	66,670,000
Gross Unrealized Gains	486,000	708,000
Gross Unrealized Losses	(423,000)	(304,000)
Fair Value	47,392,000	67,074,000
Municipal General Obligation Bonds [Member]
Amortized Cost	120,284,000	120,679,000
Gross Unrealized Gains	312,000	1,549,000
Gross Unrealized Losses	(1,549,000)	(205,000)
Fair Value	119,047,000	122,023,000
Municipal Revenue Bonds [Member]
Amortized Cost	7,699,000	8,841,000
Gross Unrealized Gains	23,000	76,000
Gross Unrealized Losses	(91,000)	(3,000)
Fair Value	7,631,000	8,914,000
Other Debt Obligations [Member]
Amortized Cost	1,979,000	1,946,000
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(29,000)	(5,000)
Fair Value	$ 1,950,000	$ 1,941,000