Note 3 - Debt Securities - Amortized Cost and Fair Value of Municipal Securities by State, Including Gross Unrealized Gains and Losses (Details) - US States and Political Subdivisions Debt Securities [Member] - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Percent of Municipal Portfolio	100.00%	100.00%
Municipal securities, amortized cost	$ 96,886	$ 101,552
Municipal securities, unrealized gains	912	2,203
Municipal securities, unrealized losses	(509)	(107)
Municipal securities, fair value	$ 97,289	$ 103,648
Minnesota [Member]
Percent of Municipal Portfolio	9.93%	10.12%
Municipal securities, amortized cost	$ 9,586	$ 10,280
Municipal securities, unrealized gains	88	211
Municipal securities, unrealized losses	(15)	(1)
Municipal securities, fair value	$ 9,659	$ 10,490
NEW YORK
Percent of Municipal Portfolio	9.40%	10.64%
Municipal securities, amortized cost	$ 9,063	$ 10,804
Municipal securities, unrealized gains	78	223
Municipal securities, unrealized losses
Municipal securities, fair value	$ 9,141	$ 11,027
WISCONSIN
Percent of Municipal Portfolio	9.14%	8.74%
Municipal securities, amortized cost	$ 8,914	$ 8,913
Municipal securities, unrealized gains	36	147
Municipal securities, unrealized losses	(53)
Municipal securities, fair value	$ 8,897	$ 9,060
OHIO
Percent of Municipal Portfolio	8.78%	8.36%
Municipal securities, amortized cost	$ 8,541	$ 8,551
Municipal securities, unrealized gains	47	123
Municipal securities, unrealized losses	(43)	(13)
Municipal securities, fair value	$ 8,545	$ 8,661
Massachusetts [Member]
Percent of Municipal Portfolio	8.46%	8.57%
Municipal securities, amortized cost	$ 8,165	$ 8,691
Municipal securities, unrealized gains	93	208
Municipal securities, unrealized losses	(27)	(14)
Municipal securities, fair value	$ 8,231	$ 8,885
TEXAS
Percent of Municipal Portfolio	7.55%	7.22%
Municipal securities, amortized cost	$ 7,378	$ 7,388
Municipal securities, unrealized gains	55	122
Municipal securities, unrealized losses	(91)	(21)
Municipal securities, fair value	$ 7,342	$ 7,489
CONNECTICUT
Percent of Municipal Portfolio	5.93%	6.82%
Municipal securities, amortized cost	$ 5,715	$ 6,929
Municipal securities, unrealized gains	53	142
Municipal securities, unrealized losses
Municipal securities, fair value	$ 5,768	$ 7,071
IOWA
Percent of Municipal Portfolio	5.20%	5.27%
Municipal securities, amortized cost	$ 5,138	$ 5,463
Municipal securities, unrealized gains	10	30
Municipal securities, unrealized losses	(90)	(35)
Municipal securities, fair value	$ 5,058	$ 5,458
NEW JERSEY
Percent of Municipal Portfolio	4.74%	4.67%
Municipal securities, amortized cost	$ 4,521	$ 4,670
Municipal securities, unrealized gains	87	167
Municipal securities, unrealized losses
Municipal securities, fair value	$ 4,608	$ 4,837
All Other States [Member]
Percent of Municipal Portfolio	30.88%	29.59%
Municipal securities, amortized cost	$ 29,865	$ 29,863
Municipal securities, unrealized gains	365	830
Municipal securities, unrealized losses	(190)	(23)
Municipal securities, fair value	$ 30,040	$ 30,670