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Employee Benefit Plans (Textual) (Details) |  |  | 12 Months Ended
--- | --- | --- | ---
Jan. 25, 2018 $ / shares shares | Aug. 04, 2017 $ / shares shares | Dec. 31, 2018 USD ($) plan shares | Dec. 31, 2017 USD ($) shares
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Deferred compensation arrangements, overall, description |  |  | After one year of service the Company matches 100 percent of employee contributions up to 3 percent of compensation and 50 percent of employee contributions on the next 2 percent of compensation. |
Number of stock option plans | plan |  |  | 1 |
Number of inactive stock option plans with outstanding grants | plan |  |  | 4 |
Share-based compensation expense |  |  | $ 133,884 | $ 97,966
Options vested in period, fair value |  |  | 243,831 | 313,977
Deferred tax expense from stock options exercised |  |  | 318,826 | 1,331,689
Options, exercises in period, intrinsic value |  |  | 1,523,014 | $ 5,468,780
Options, outstanding, intrinsic value |  |  | 1,307,043 |
Options, exercisable, intrinsic value |  |  | 1,263,872 |
Proceeds from stock options exercised |  |  | $ 1,519,244 |
Number of shares granted (in shares) | shares |  |  | 0 | 0
Director [Member] |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Direct stock grant expense |  |  | $ 9,062 | $ 31,791
Deferred Salary Reduction Plan [Member] |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Defined contribution plan, cost recognized |  |  | 715,698 | 427,975
Stock Appreciation Rights (SARs) [Member] |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Share-based compensation expense |  |  | 33,916 | 21,829
Stock Options [Member] |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Unrecognized compensation costs |  |  | $ 124,450 |
Unrecognized compensation costs, period for recognition |  |  | 1 year |
Restricted Stock [Member] |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Number of shares granted (in shares) | shares |  |  | 7,553 |
Vested (in shares) | shares |  |  | 5,553 |
Legacy Cornerstone Bancshares, Inc. Long-Term Incentive Plan [Member] |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Exercise price, not less than (as a percent) |  |  | 100.00% |
2015 Stock Incentive Plan [Member] |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Exercise price, not less than (as a percent) |  |  | 110.00% |
Number outstanding (in shares) | shares |  |  | 2,000,000 |
Term of options, no more than |  |  | 10 years |
Voting power held by participant (as a percent) |  |  | 10.00% |
Term of option to participants with more than ten percent voting power |  |  | 5 years |
Percentage of incentive stock options vesting on second anniversary |  |  | 30.00% |
Percentage of incentive stock options vesting on third anniversary |  |  | 30.00% |
Percentage of incentive stock options vesting on fourth anniversary |  |  | 40.00% |
Percentage of nonqualified stock options vesting on first anniversary |  |  | 50.00% |
Percentage of nonqualified stock options vesting on second anniversary |  |  | 50.00% |
2015 Stock Incentive Plan [Member] | Nonstatutory Stock Option [Member] |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Exercise price, not less than (as a percent) |  |  | 100.00% |
2015 Stock Incentive Plan [Member] | Restricted Stock [Member] |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Share-based compensation expense |  |  | $ 263,013 | $ 56,330
Number of shares granted (in shares) | shares | 7,553 | 27,500 |  |
Grant date fair value (in dollars per share) | $ / shares | $ 21.61 | $ 24.58 |  |
Unrecognized compensation cost |  |  | $ 519,727 |
Legacy Capstone Stock Option Plan [Member] |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Exercise price, not less than (as a percent) |  |  | 100.00% |
401 (k) Matching Range One [Member] | Deferred Salary Reduction Plan [Member] |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Request service period |  |  | 1 year |
Employer matching contribution, percent of match |  |  | 100.00% |
Employer matching contribution, percent of employees gross pay |  |  | 3.00% |
401 (k) Matching Range Two [Member] | Deferred Salary Reduction Plan [Member] |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Employer matching contribution, percent of match |  |  | 50.00% |
Employer matching contribution, percent of employees gross pay |  |  | 2.00% |
Share-based Compensation Award, Tranche Three [Member] | 2015 Stock Incentive Plan [Member] | Restricted Stock [Member] |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Term of option to participants with more than ten percent voting power |  |  | 5 years |
Vested (in shares) | shares | 2,000 |  |  |
Share-based Compensation Award, Tranche Two [Member] | 2015 Stock Incentive Plan [Member] | Restricted Stock [Member] |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Term of option to participants with more than ten percent voting power |  |  | 6 months |
Share-based Compensation Award, Tranche Two [Member] | 2015 Stock Incentive Plan [Member] | Restricted Stock [Member] | Director [Member] |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Vested (in shares) | shares | 926 |  |  |
Share-based Compensation Award, Tranche One [Member] | 2015 Stock Incentive Plan [Member] | Restricted Stock [Member] |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Vested (in shares) | shares | 4,627 |  |  |

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