Note 9 - Regulatory Matters Subsequent Event - Risk-based Capital and Related Ratios (Details) - USD ($) $ in Thousands		Mar. 31, 2019	Dec. 31, 2018
Total capital (to risk-weighted assets), Amount		$ 138,537	$ 117,213
Total capital (to risk-weighted assets), Ratio		15.06%	12.69%
Total capital (to risk-weighted assets), Minimum required for capital adequacy purposes		8.00%	8.00%
Total capital (to risk-weighted assets), Minimum required for capital adequacy purposes with conservation buffer		10.50%	9.875%
Total capital (to risk-weighted assets), To be well capitalized under prompt corrective action	[1]	10.00%	10.00%
Tier I capital (to risk-weighted assets), Amount		$ 129,009	$ 105,439
Tier I capital (to risk-weighted assets), Ratio		14.03%	11.42%
Tier I capital (to risk-weighted assets), Minimum required for capital adequacy purposes		6.00%	6.00%
Tier I capital (to risk-weighted assets), Minimum required for capital adequacy purposes with conservation buffer		8.50%	7.875%
Tier I capital (to risk-weighted assets), To be well capitalized under prompt corrective action	[1]	8.00%	8.00%
Tier I common equity (to risk-weighted assets), Amount		$ 119,009	$ 96,692
Tier I common equity (to risk-weighted assets), Ratio		12.94%	10.47%
Tier I common equity (to risk-weighted assets), Minimum required for capital adequacy purposes		4.50%	4.50%
Tier I common equity (to risk-weighted assets), Minimum required for capital adequacy purposes with conservation buffer		7.00%	6.375%
Tier I common equity (to risk-weighted assets), To be well capitalized under prompt corrective action	[1]	6.50%	6.50%
Tier I capital (to average assets), Amount		$ 129,009	$ 105,439
Tier I capital (to average assets), Ratio		10.45%	8.50%
Tier I capital (to average assets), Minimum required for capital adequacy purposes		4.00%	4.00%
Tier I capital (to average assets), Minimum required for capital adequacy purposes with conservation buffer		4.00%	4.00%
Tier I capital (to average assets), To be well capitalized under prompt corrective action	[1]	5.00%	5.00%
Total risk-weighted assets, Amount		$ 919,672	$ 923,441
Total average assets, Amount		1,234,306	1,239,898
Subsidiaries [Member]
Total capital (to risk-weighted assets), Amount		$ 132,980	$ 112,128
Total capital (to risk-weighted assets), Ratio		14.49%	12.17%
Tier I capital (to risk-weighted assets), Amount		$ 123,452	$ 102,354
Tier I capital (to risk-weighted assets), Ratio		13.45%	11.11%
Tier I common equity (to risk-weighted assets), Amount		$ 123,452	$ 102,354
Tier I common equity (to risk-weighted assets), Ratio		13.45%	11.11%
Tier I capital (to average assets), Amount		$ 123,452	$ 102,354
Tier I capital (to average assets), Ratio		10.07%	8.27%
Total risk-weighted assets, Amount		$ 917,523	$ 921,126
Total average assets, Amount		$ 1,226,302	$ 1,238,347

[1] Applies to the Bank only.