Note 2 - Securities - Available-for-sale Securities (Details) - USD ($)	Jun. 30, 2017	Dec. 31, 2016
Gross Unrealized Losses	$ (4,032,000)	$ (9,429,000)
Fair Value	322,258,000	328,060,000
Amortized Cost	323,548,000	336,562,000
Gross Unrealized Gains	2,742,000	927,000
US Government Agencies Debt Securities [Member]
Gross Unrealized Losses	(3,618,000)	(7,337,000)
Fair Value	154,650,000	152,040,000
Amortized Cost	157,873,000	159,271,000
Gross Unrealized Gains	395,000	106,000
Collateralized Mortgage Backed Securities [Member]
Gross Unrealized Losses	(164,000)	(423,000)
Fair Value	40,199,000	47,392,000
Amortized Cost	39,873,000	47,329,000
Gross Unrealized Gains	490,000	486,000
Municipal General Obligation Bonds [Member]
Gross Unrealized Losses	(208,000)	(1,549,000)
Fair Value	120,484,000	119,047,000
Amortized Cost	118,893,000	120,284,000
Gross Unrealized Gains	1,799,000	312,000
Municipal Revenue Bonds [Member]
Gross Unrealized Losses	(21,000)	(91,000)
Fair Value	4,952,000	7,631,000
Amortized Cost	4,915,000	7,699,000
Gross Unrealized Gains	58,000	23,000
Other Debt and Equity Securities [Member]
Gross Unrealized Losses	(21,000)	(29,000)
Fair Value	1,973,000	1,950,000
Amortized Cost	1,994,000	1,979,000
Gross Unrealized Gains	$ 0	$ 0