Regulatory Matters (Regulatory capital amounts and ratios) (Details) - Security Federal Bank [Member] - USD ($)	Mar. 31, 2020	Dec. 31, 2019
Tier 1 Risk-Based Core Capital (To Risk Weighted Assets)
Actual, Amount	$ 102,698,000	$ 101,280,000
Actual, Ratio	18.28408%	18.18401%
For Capital Adequacy, Amount	$ 33,700,800	$ 33,418,380
For Capital Adequacy, Ratio	6.00%	6.00%
To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 44,934,000	$ 44,558,000
To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	8.00%	8.00%
Total Risk-Based Capital (To Risk Weighted Assets)
Actual, Amount	$ 109,754,000	$ 108,270,000
Actual, Ratio	19.54031%	19.439%
For Capital Adequacy, Amount	$ 44,934,400	$ 44,557,840
For Capital Adequacy, Ratio	8.00%	8.00%
To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 56,168,000	$ 55,697,000
To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	10.00%	10.00%
Common Equity Tier One Capital	$ 102,698,000	$ 101,280,000
Common Equity Tier One Capital Ratio	18.28408%	18.18401%
Common Equity Tier One Capital Required for Capital Adequacy	$ 25,275,600	$ 25,063,785
Common Equity Tier One Capital Required to be Well-Capitalized	36,509,000	36,203,000
Tier 1 Leverage (Core) Capital (To Adjusted Tangible Assets)
Actual, Amount	$ 102,698,000	$ 101,280,000
Actual, Ratio	10.30327%	10.35218%
For Capital Adequacy, Amount	$ 39,870,080	$ 39,133,800
For Capital Adequacy, Ratio	4.00%	4.00%
To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 49,838,000	$ 48,917,000
To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	5.00%	5.00%