Note 10 - Intangible Assets - Gross Carrying Amount and Accumulated Amortization of Intangible Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Finite-lived intangible assets, accumulated amortization	$ (2,802)		$ (2,567)
Finite-lived intangible assets, unamortized intangible assets		$ 2,054
Goodwill, gross carrying amount	802		802
Goodwill, accumulated impairment	0		0
Goodwill	802	802	802
Intangible assets (including goodwill), gross carrying amount	5,658		5,422
Intangible assets, unamortized intangible assets	2,856		2,855
Mortgage Servicing Rights [Member]
Finite-lived intangible assets, gross carrying amount	4,282		4,046
Finite-lived intangible assets, accumulated amortization	(2,558)		(2,422)
Finite-lived intangible assets, unamortized intangible assets	1,724	1,724	1,624
Core Deposits [Member]
Finite-lived intangible assets, gross carrying amount	574		574
Finite-lived intangible assets, accumulated amortization	(244)		(145)
Finite-lived intangible assets, unamortized intangible assets	$ 330	$ 330	$ 429