Minimum Capital Requirements (Details) $ in Thousands	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
FB Financial Corporation
Total Capital (to risk-weighted assets)
Actual, Amount	$ 1,528,344	$ 1,434,581
Actual, Ratio	0.131	0.145
Minimum Capital adequacy with capital buffer, Amount	$ 1,225,161	$ 1,039,984
Minimum Capital adequacy with capital buffer, Ratio	0.105	0.105
Tier 1 Capital (to risk-weighted assets)
Actual, Amount	$ 1,315,386	$ 1,251,874
Actual, Ratio	0.113	0.126
Minimum Capital adequacy with capital buffer, Amount	$ 991,797	$ 841,892
Minimum Capital adequacy with capital buffer, Ratio	8.50%	8.50%
Tier 1 Capital (to average assets)
Actual, Amount	$ 1,315,386	$ 1,251,874
Actual, Ratio	0.105	0.105
Minimum Capital adequacy with capital buffer, Amount	$ 499,648	$ 474,831
Minimum Capital adequacy with capital buffer. Ratio	0.040	0.040
Common Equity Tier 1 Capital (to risk-weighted assets)
Actual, Amount	$ 1,285,386	$ 1,221,874
Actual Ratio	11.00%	12.30%
Minimum Capital adequacy with capital buffer, Amount	$ 816,774	$ 693,322
Minimum Capital adequacy with capital buffer, Ratio	0.070	0.070
FirstBank
Total Capital (to risk-weighted assets)
Actual, Amount	$ 1,506,543	$ 1,396,407
Actual, Ratio	0.129	0.141
Minimum Capital adequacy with capital buffer, Amount	$ 1,222,922	$ 1,038,760
Minimum Capital adequacy with capital buffer, Ratio	0.105	0.105
To be well capitalized under prompt corrective action provisions, Amount	$ 1,164,688	$ 989,295
To be well capitalized under prompt corrective action provisions, Ratio	0.100	0.100
Tier 1 Capital (to risk-weighted assets)
Actual, Amount	$ 1,293,585	$ 1,213,700
Actual, Ratio	0.111	0.123
Minimum Capital adequacy with capital buffer, Amount	$ 989,985	$ 840,901
Minimum Capital adequacy with capital buffer, Ratio	8.50%	8.50%
To be well capitalized under prompt corrective action provisions, Amount	$ 931,750	$ 791,436
To be well capitalized under prompt corrective action provisions, Ratio	0.080	0.080
Tier 1 Capital (to average assets)
Actual, Amount	$ 1,293,585	$ 1,213,700
Actual, Ratio	0.104	0.102
Minimum Capital adequacy with capital buffer, Amount	$ 499,194	$ 474,044
Minimum Capital adequacy with capital buffer. Ratio	0.040	0.040
To be well capitalized under prompt corrective action provisions, Amount	$ 623,992	$ 592,555
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	$ 1,293,585	$ 1,213,700
Actual Ratio	11.10%	12.30%
Minimum Capital adequacy with capital buffer, Amount	$ 815,281	$ 692,507
Minimum Capital adequacy with capital buffer, Ratio	0.070	0.070
To be well capitalized under prompt corrective action provisions, Amount	$ 757,047	$ 643,042
To be well capitalized under prompt corrective action provisions, Ratio	6.50%	6.50%