Regulatory Matters (Regulatory capital amounts and ratios) (Details) - USD ($)	Jun. 30, 2017	Dec. 31, 2016
Tier 1 Risk-Based Core Capital (To Risk Weighted Assets)
Actual, Amount	$ 76,333,000	$ 73,787,109
Actual, Ratio	17.70%	16.57282%
For Capital Adequacy, Amount	$ 25,894,800	$ 26,713,740
For Capital Adequacy, Ratio	6.00%	6.00%
Total Risk-Based Capital (To Risk Weighted Assets)
Actual, Amount	$ 82,131,000	$ 79,383,109
Actual, Ratio	19.00%	17.8297%
For Capital Adequacy, Amount	$ 34,526,400	$ 35,618,320
For Capital Adequacy, Ratio	8.00%	8.00%
Common Equity Tier One Capital	$ 71,333,000	$ 68,787,109
Common Equity Tier One Capital Ratio	16.50%	15.4498%
Common Equity Tier One Capital Required for Capital Adequacy	$ 19,421,100	$ 20,035,305
Tier 1 Leverage (Core) Capital (To Adjusted Tangible Assets)
Actual, Amount	$ 76,333,000	$ 73,787,109
Actual, Ratio	9.00%	9.06805%
For Capital Adequacy, Amount	$ 33,809,080	$ 32,548,120
For Capital Adequacy, Ratio	4.00%	4.00%
Security Federal Bank [Member]
Tier 1 Risk-Based Core Capital (To Risk Weighted Assets)
Actual, Amount	$ 88,325,000	$ 88,139,000
Actual, Ratio	19.14179%	19.81097%
For Capital Adequacy, Amount	$ 27,685,500	$ 26,694,000
For Capital Adequacy, Ratio	6.00%	6.00%
To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 36,914,000	$ 35,592,000
To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	8.00%	8.00%
Total Risk-Based Capital (To Risk Weighted Assets)
Actual, Amount	$ 94,123,000	$ 93,735,000
Actual, Ratio	20.39833%	21.06878%
For Capital Adequacy, Amount	$ 36,914,000	$ 35,592,000
For Capital Adequacy, Ratio	8.00%	8.00%
To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 46,143,000	$ 44,490,000
To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	10.00%	10.00%
Common Equity Tier One Capital	$ 88,325,000	$ 88,139,000
Common Equity Tier One Capital Ratio	19.14179%	19.81097%
Common Equity Tier One Capital Required for Capital Adequacy	$ 20,764,125	$ 20,020,500
Common Equity Tier One Capital Required to be Well-Capitalized	29,993,000	28,919,000
Tier 1 Leverage (Core) Capital (To Adjusted Tangible Assets)
Actual, Amount	$ 88,325,000	$ 88,139,000
Actual, Ratio	10.45428%	10.81897%
For Capital Adequacy, Amount	$ 33,794,760	$ 32,586,840
For Capital Adequacy, Ratio	4.00%	4.00%
To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 42,243,000	$ 40,734,000
To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	5.00%	5.00%