Employee Benefit Plans (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
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.
Share-based compensation expense	$ 132,635	$ 140,077
Options vested in period, fair value	95,658	103,604
Deferred tax expense from stock options exercised	660,567	27,738
Options, exercises in period, intrinsic value	660,476	171,574
Options, outstanding, intrinsic value	6,074,252
Options, exercisable, intrinsic value	5,905,718
Proceeds from stock options exercised	$ 803,957
Number of shares granted	0
Weighted average grant-date fair value, granted (in dollars per share)	$ 0.00
Deferred Salary Reduction Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan, cost recognized	$ 403,309	219,017
Director [Member]
Defined Benefit Plan Disclosure [Line Items]
Direct stock grant expense		$ 100,216
Stock Options [Member]
Defined Benefit Plan Disclosure [Line Items]
Unrecognized compensation costs	$ 365,000
Unrecognized compensation costs, period for recognition	4 years
Weighted average grant-date fair value, granted (in dollars per share)		$ 12.31
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%
Smart Bank Stock Option Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Number of shares authorized	525,000
Exercise price, not less than (as a percent)	100.00%
Legacy Smart Financial Inc 2010 Incentive Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Number of shares authorized	525,000
Exercise price, not less than (as a percent)	100.00%
Stock Incentive Plan Two Thousand Fifteen [Member]
Defined Benefit Plan Disclosure [Line Items]
Exercise price, not less than (as a percent)	110.00%
Number Outstanding (in 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%
401 (k) Matching Range One [Member] | Deferred Salary Reduction Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer matching contribution, percent of employees gross pay	3.00%
Employer matching contribution, percent of match	100.00%
401 (k) Matching Range Two [Member] | Deferred Salary Reduction Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer matching contribution, percent of employees gross pay	2.00%
Employer matching contribution, percent of match	50.00%