Regulatory Matters (Regulatory Capital Levels) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
SmartFinancial, Inc. [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital (to Risk-Weighted Assets), Actual Amount	$ 287,937	$ 257,545
Tier 1 Capital (to Risk-Weighted Assets), Actual Amount	238,433	210,093
Common Equity Tier 1 Capital (to Risk-Weighted Assets), Actual Amount	238,433	210,093
Tier 1 Capital (to Average Assets), Actual Amount	$ 238,433	$ 210,093
Total Capital (to Risk-Weighted Assets), Actual Ratio (as a percent)	14.02%	13.47%
Tier 1 Capital (to Risk-Weighted Assets), Actual Ratio (as a percent)	11.61%	10.99%
Common Equity Tier 1 Capital (to Risk-Weighted Assets), Actual Ratio (as a percent)	11.61%	10.99%
Tier 1 Capital (to Average Assets), Actual Ratio (as a percent)	10.34%	9.91%
Total Capital (to Risk-Weighted Assets), Minimum for capital adequacy purposes Amount	$ 164,313	$ 152,971
Tier 1 Capital (to Risk-Weighted Assets), Minimum for capital adequacy purposes Amount	123,235	114,728
Common Equity Tier 1 Capital (to Risk-Weighted Assets), Minimum for capital adequacy purposes Amount	92,426	86,046
Tier 1 Capital (to Average Assets), Minimum for capital adequacy purposes Amount	$ 92,258	$ 84,821
Total Capital (to Risk-Weighted Assets), Minimum for capital adequacy purposes Ratio (as a percent)	8.00%	8.00%
Tier 1 Capital (to Risk-Weighted Assets), Minimum for capital adequacy purposes Ratio (as a percent)	6.00%	6.00%
Common Equity Tier 1 Capital (to Risk-Weighted Assets), Minimum for capital adequacy purposes Ratio (as a percent)	4.50%	4.50%
Tier 1 Capital (to Average Assets), Minimum for capital adequacy purposes Ratio (as a percent)	4.00%	4.00%
Smart Bank [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital (to Risk-Weighted Assets), Actual Amount	$ 273,432	$ 243,774
Tier 1 Capital (to Risk-Weighted Assets), Actual Amount	263,189	235,499
Common Equity Tier 1 Capital (to Risk-Weighted Assets), Actual Amount	263,189	235,499
Tier 1 Capital (to Average Assets), Actual Amount	$ 263,189	$ 235,499
Total Capital (to Risk-Weighted Assets), Actual Ratio (as a percent)	13.31%	12.74%
Tier 1 Capital (to Risk-Weighted Assets), Actual Ratio (as a percent)	12.81%	12.31%
Common Equity Tier 1 Capital (to Risk-Weighted Assets), Actual Ratio (as a percent)	12.81%	12.31%
Tier 1 Capital (to Average Assets), Actual Ratio (as a percent)	11.41%	11.17%
Total Capital (to Risk-Weighted Assets), Minimum for capital adequacy purposes Amount	$ 164,305	$ 153,017
Tier 1 Capital (to Risk-Weighted Assets), Minimum for capital adequacy purposes Amount	123,229	114,763
Common Equity Tier 1 Capital (to Risk-Weighted Assets), Minimum for capital adequacy purposes Amount	92,422	86,072
Tier 1 Capital (to Average Assets), Minimum for capital adequacy purposes Amount	$ 92,254	$ 84,300
Total Capital (to Risk-Weighted Assets), Minimum for capital adequacy purposes Ratio (as a percent)	8.00%	8.00%
Tier 1 Capital (to Risk-Weighted Assets), Minimum for capital adequacy purposes Ratio (as a percent)	6.00%	6.00%
Common Equity Tier 1 Capital (to Risk-Weighted Assets), Minimum for capital adequacy purposes Ratio (as a percent)	4.50%	4.50%
Tier 1 Capital (to Average Assets), Minimum for capital adequacy purposes Ratio (as a percent)	4.00%	4.00%
Total Capital (to Risk-Weighted Assets), Minimum to be well capitalized under prompt corrective action provisions Amount	$ 205,382	$ 191,271
Tier 1 Capital (to Risk-Weighted Assets), Minimum to be well capitalized under prompt corrective action provisions Amount	164,305	153,017
Common Equity Tier 1 Capital (to Risk-Weighted Assets), Minimum to be well capitalized under prompt corrective action provisions Amount	133,498	124,326
Tier 1 Capital (to Average Assets), Minimum to be well capitalized under prompt corrective action provisions Amount	$ 115,317	$ 105,375
Total Capital (to Risk-Weighted Assets), Minimum to be well capitalized under prompt corrective action provisions Ratio (as a percent)	10.00%	10.00%
Tier 1 Capital (to Risk-Weighted Assets), Minimum to be well capitalized under prompt corrective action provisions Ratio (as a percent)	8.00%	8.00%
Common Equity Tier 1 Capital (to Risk-Weighted Assets), Minimum to be well capitalized under prompt corrective action provisions Ratio (as a percent)	6.50%	6.50%
Tier 1 Capital (to Average Assets), Minimum to be well capitalized under prompt corrective action provisions Ratio (as a percent)	5.00%	5.00%

Common equity Tier 1 Risk Based Capital as defined in the regulations.

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The minimum common equity Tier One Capital Ratio (Common equity Tier one capital divided by risk-weighted assets) required for capital adequacy purposes under the regulatory framework for prompt corrective action.

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The amount of common equity Tier 1 Risk Based Capital required to be categorized as well capitalized under the regulatory framework for prompt corrective action.

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Common equity Tier 1 capital divided by risk weighted assets as defined by regulations.

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The amount of total capital as defined in the regulations.

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The minimum amount of Total Capital required for capital adequacy purposes under the regulatory framework for prompt corrective action.

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The minimum Total risk based capital ratio (total capital divided by risk weighted assets) required for capital adequacy purposes under the regulatory framework for prompt corrective action.

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The amount of Total Capital required to be categorized as well as capitalized under the regulatory framework for prompt corrective action.

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The Total risk based capital ratio (total capital divided by risk weighted assets) required to be categorized as "well capitalized", in the regulatory framework for prompt corrective action.

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Total Capital divided by risk weighted assets as defined in the regulations.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Tier 1 Leverage Capital as defined in the regulations. Also called Core Capital.

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Tier 1 Leverage Capital divided by average assets as defined in the regulations.

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Tier 1 Risk Based Capital as defined in the regulations.

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Tier 1 capital divided by risk weighted assets as defined by regulations.

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