Note 8 - Fair Values - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands		Jun. 30, 2018	Dec. 31, 2017
Securities available-for-sale		$ 247,639	$ 267,954
Fair Value, Measurements, Recurring [Member]
Total assets measured at fair value		247,639	267,954
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Total assets measured at fair value
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Total assets measured at fair value		247,639	267,954
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Total assets measured at fair value
US Government Agencies Debt Securities [Member]
Securities available-for-sale		38,994	40,369
US Government Agencies Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]
Securities available-for-sale		38,994	40,369
US Government Agencies Debt Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale
US Government Agencies Debt Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale		38,994	40,369
US Government Agencies Debt Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
US States and Political Subdivisions Debt Securities [Member]
Securities available-for-sale		58,479	78,844
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]
Securities available-for-sale		58,479	78,844
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale		58,479	78,844
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
Residential Mortgage Backed Securities and Collateralized Mortgage Obligations [Member]
Securities available-for-sale		121,218	114,592
Residential Mortgage Backed Securities and Collateralized Mortgage Obligations [Member] | Fair Value, Measurements, Recurring [Member]
Securities available-for-sale		121,218	114,592
Residential Mortgage Backed Securities and Collateralized Mortgage Obligations [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale
Residential Mortgage Backed Securities and Collateralized Mortgage Obligations [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale		121,218	114,592
Residential Mortgage Backed Securities and Collateralized Mortgage Obligations [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
Corporate Debt Securities [Member]
Securities available-for-sale		3,987	4,992
Corporate Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]
Securities available-for-sale		3,987	4,992
Corporate Debt Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale
Corporate Debt Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale		3,987	4,992
Corporate Debt Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
Commercial Mortgage Backed Securities [Member]
Securities available-for-sale		24,742	26,641
Commercial Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Securities available-for-sale		24,742	26,641
Commercial Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale
Commercial Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale		24,742	26,641
Commercial Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
Asset-backed Securities [Member]
Securities available-for-sale		219	2,516
Asset-backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Securities available-for-sale		219
Asset-backed Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale
Asset-backed Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale		219
Asset-backed Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
Other Debt Obligations [Member] | Fair Value, Measurements, Recurring [Member]
Securities available-for-sale	[1]		2,516
Other Debt Obligations [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale	[1]
Other Debt Obligations [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale	[1]		2,516
Other Debt Obligations [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale	[1]

[1] Principally consists of asset-backed securities and CRA qualified mutual fund investments.