Minimum Capital Requirements (Details) $ in Thousands	Jun. 30, 2023 USD ($)	Dec. 31, 2022 USD ($)
FB Financial Corporation
Total Capital (to risk-weighted assets)
Actual, Amount	$ 1,588,399	$ 1,528,344
Actual, Ratio	0.139	0.131
Minimum Capital adequacy with capital buffer, Amount	$ 1,198,463	$ 1,225,161
Minimum Capital adequacy with capital buffer, Ratio	0.105	0.105
Tier 1 Capital (to risk-weighted assets)
Actual, Amount	$ 1,363,796	$ 1,315,386
Actual, Ratio	0.119	0.113
Minimum Capital adequacy with capital buffer, Amount	$ 970,185	$ 991,797
Minimum Capital adequacy with capital buffer, Ratio	8.50%	8.50%
Tier 1 Capital (to average assets)
Actual, Amount	$ 1,363,796	$ 1,315,386
Actual, Ratio	0.107	0.105
Minimum Capital adequacy with capital buffer, Amount	$ 510,676	$ 499,648
Minimum Capital adequacy with capital buffer. Ratio	0.040	0.040
Common Equity Tier 1 Capital (to risk-weighted assets)
Actual, Amount	$ 1,333,796	$ 1,285,386
Actual Ratio	11.70%	11.00%
Minimum Capital adequacy with capital buffer, Amount	$ 798,976	$ 816,774
Minimum Capital adequacy with capital buffer, Ratio	0.070	0.070
FirstBank
Total Capital (to risk-weighted assets)
Actual, Amount	$ 1,555,006	$ 1,506,543
Actual, Ratio	0.136	0.129
Minimum Capital adequacy with capital buffer, Amount	$ 1,196,301	$ 1,222,922
Minimum Capital adequacy with capital buffer, Ratio	0.105	0.105
To be well capitalized under prompt corrective action provisions, Amount	$ 1,139,334	$ 1,164,688
To be well capitalized under prompt corrective action provisions, Ratio	0.100	0.100
Tier 1 Capital (to risk-weighted assets)
Actual, Amount	$ 1,330,403	$ 1,293,585
Actual, Ratio	0.117	0.111
Minimum Capital adequacy with capital buffer, Amount	$ 968,434	$ 989,985
Minimum Capital adequacy with capital buffer, Ratio	8.50%	8.50%
To be well capitalized under prompt corrective action provisions, Amount	$ 911,467	$ 931,750
To be well capitalized under prompt corrective action provisions, Ratio	0.080	0.080
Tier 1 Capital (to average assets)
Actual, Amount	$ 1,330,403	$ 1,293,585
Actual, Ratio	0.104	0.104
Minimum Capital adequacy with capital buffer, Amount	$ 510,283	$ 499,194
Minimum Capital adequacy with capital buffer. Ratio	0.040	0.040
To be well capitalized under prompt corrective action provisions, Amount	$ 637,854	$ 623,992
To be well capitalized under prompt corrective action provisions, Ratio	0.050	0.050
Common Equity Tier 1 Capital (to risk-weighted assets)
Actual, Amount	$ 1,330,403	$ 1,293,585
Actual Ratio	11.70%	11.10%
Minimum Capital adequacy with capital buffer, Amount	$ 797,534	$ 815,281
Minimum Capital adequacy with capital buffer, Ratio	0.070	0.070
To be well capitalized under prompt corrective action provisions, Amount	$ 740,567	$ 757,047
To be well capitalized under prompt corrective action provisions, Ratio	6.50%	6.50%