Note 5 - Securities - Securities in a Continuous Loss Position (Details) - USD ($)	Sep. 30, 2016	Dec. 31, 2015
US Government Agencies Debt Securities [Member]
Securities in a Continuours Loss Position, Less Than 12 Months, Fair Value	$ 90,723,000	$ 88,255,000
Securities in a Continuours Loss Position, Less Than 12 Months, Unrealized Loss	253,000	1,800,000
Securities in a Continuours Loss Position, 12 Months or More, Fair Value	0	84,959,000
Securities in a Continuours Loss Position, 12 Months or More, Unrealized Loss	0	3,329,000
US States and Political Subdivisions Debt Securities [Member]
Securities in a Continuours Loss Position, Less Than 12 Months, Fair Value	780,000	3,449,000
Securities in a Continuours Loss Position, Less Than 12 Months, Unrealized Loss	1,000	24,000
Securities in a Continuours Loss Position, 12 Months or More, Fair Value	1,440,000	10,161,000
Securities in a Continuours Loss Position, 12 Months or More, Unrealized Loss	24,000	306,000
Other Securities [Member]
Securities in a Continuours Loss Position, Less Than 12 Months, Fair Value	0	0
Securities in a Continuours Loss Position, Less Than 12 Months, Unrealized Loss	0	0
Securities in a Continuours Loss Position, 12 Months or More, Fair Value	152,000	127,000
Securities in a Continuours Loss Position, 12 Months or More, Unrealized Loss	37,000	62,000
Corporate Debt Securities [Member]
Securities in a Continuours Loss Position, Less Than 12 Months, Fair Value		4,974,000
Securities in a Continuours Loss Position, Less Than 12 Months, Unrealized Loss		292,000
Securities in a Continuours Loss Position, 12 Months or More, Fair Value		200,000
Securities in a Continuours Loss Position, 12 Months or More, Unrealized Loss		1,000
Securities in a Continuours Loss Position, Less Than 12 Months, Fair Value	91,503,000	96,678,000
Securities in a Continuours Loss Position, Less Than 12 Months, Unrealized Loss	254,000	2,116,000
Securities in a Continuours Loss Position, 12 Months or More, Fair Value	1,592,000	95,447,000
Securities in a Continuours Loss Position, 12 Months or More, Unrealized Loss	$ 61,000	$ 3,698,000