Regulatory Matters - Capital amounts and ratios (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Total risk-based capital (to risk-weighted assets), Actual Amount	$ 24,237	$ 24,480
Total risk-based capital (to risk-weighted assets), Actual Ratio	16.50%	17.50%
Total risk-based capital (to risk-weighted assets), Minimum Capital Requirement Amount	$ 11,743	$ 11,176
Total risk-based capital (to risk-weighted assets), Minimum Capital Requirement Ratio	8.00%	8.00%
Total risk-based capital (to risk-weighted assets), minimum to Be Well Capitalized Under Prompt Corrective Action Provisions Amount	$ 14,679	$ 13,970
Total risk-based capital (to risk-weighted assets), Minimum to Be Well Capitalized Under Prompt Corrective Action Provisions Ratio	10.00%	10.00%
Tier I capital (to risk-weighted assets), Actual Amount	$ 22,832	$ 23,075
Tier I capital (to risk-weighted assets), Actual Ratio	15.60%	16.50%
Tier I capital (to risk-weighted assets), Minimum Capital Requirement Amount	$ 8,807	$ 8,382
Tier I capital (to risk-weighted assets), Minimum Capital Requirement Ratio	6.00%	6.00%
Tier I capital (to risk-weighted assets), Minimum to Be Well Capitalized Under Prompt Corrective Action Provisions Amount	$ 11,743	$ 11,176
Tier I capital (to risk-weighted assets), Minimum to Be Well Capitalized Under Prompt Corrective Action Provisions Ratio	8.00%	8.00%
Tier I capital (to adjusted total assets), Actual Amount	$ 22,832	$ 23,075
Tier I capital (to adjusted total assets), Actual Ratio	11.10%	11.50%
Tier I capital (to adjusted total assets), Minimum Capital Requirement Amount	$ 8,245	$ 8,014
Tier I capital (to adjusted total assets), Minimum Capital Requirement Ratio	4.00%	4.00%
Tier I capital (to adjusted total assets), Minimum to Be Well Capitalized Under Prompt Corrective Action Provisions Amount	$ 10,306	$ 10,017
Tier I capital (to adjusted total assets), Minimum to Be Well Capitalized Under Prompt Corrective Action Provisions Ratio	5.00%	5.00%
Common Stock [Member]
Common Equity Tier I capital (to risk-weighted assets), Actual Amount	$ 22,832	$ 23,075
Common Equity Tier I capital (to risk-weighted assets), Actual Ratio	15.60%	16.50%
Common Equity Tier I capital (to risk-weighted assets), Minimum Capital Requirement Amount	$ 6,606	$ 6,287
Common Equity Tier I capital (to risk-weighted assets), Minimum Capital Requirement Ratio	4.50%	4.50%
Common Equity Tier I capital (to risk-weighted assets), Minimum to Be Well Capitalized Under Prompt Corrective Action Provisions Amount	$ 9,541	$ 9,081
Common Equity Tier I capital (to risk-weighted assets), Minimum to Be Well Capitalized Under Prompt Corrective Action Provisions Ratio	6.50%	6.50%

Cincinnati Bancorp 10-Q