Minimum capital requirements (Tables)

12 Months Ended

Dec. 31, 2020

Broker-Dealer, Net Capital Requirement, SEC Regulation [Abstract]

Schedule of Actual and Required Capital Amounts and Ratios

Actual and required capital amounts and ratios are included below for the periods presented.

	Actual				Minimum Capital adequacy with capital buffer				To be well capitalized under prompt corrective action provisions
	Amount		Ratio		Amount		Ratio		Amount		Ratio
December 31, 2020
Total Capital (to risk-weighted assets)
FB Financial Corporation	$	1,358,897	15.0	%	$	952,736	10.5	%	N/A		N/A
FirstBank	1,353,279		14.9	%	951,327		10.5	%	$	906,026	10.0	%
Tier 1 Capital (to risk-weighted assets)
FB Financial Corporation	$	1,090,364	12.0	%	$	771,262	8.5	%	N/A		N/A
FirstBank	1,142,548		12.6	%	770,122		8.5	%	$	724,820	8.0	%
Tier 1 Capital (to average assets)
FB Financial Corporation	$	1,090,364	10.0	%	$	435,064	4.0	%	N/A		N/A
FirstBank	1,142,548		10.5	%	435,279		4.0	%	$	544,098	5.0	%
Common Equity Tier 1 Capital (to risk-weighted assets)
FB Financial Corporation	$	1,060,364	11.7	%	$	635,157	7.0	%	N/A		N/A
FirstBank	1,142,548		12.6	%	634,218		7.0	%	$	588,917	6.5	%

	Actual				Minimum Capital adequacy with capital buffer				To be well capitalized under prompt corrective action provisions
	Amount		Ratio		Amount		Ratio		Amount		Ratio
December 31, 2019
Total Capital (to risk-weighted assets)
FB Financial Corporation	$	633,549	12.2	%	$	545,268	10.5	%	N/A		N/A
FirstBank	623,432		12.1	%	540,995		10.5	%	$	515,233	10.0	%
Tier 1 Capital (to risk-weighted assets)
FB Financial Corporation	$	602,410	11.6	%	$	441,421	8.50	%	N/A		N/A
FirstBank	592,293		11.5	%	437,782		8.50	%	$	412,030	8.0	%
Tier 1 Capital (to average assets)
FB Financial Corporation	$	602,410	10.1	%	$	238,578	4.00	%	N/A		N/A
FirstBank	592,293		9.9	%	239,310		4.00	%	$	299,138	5.0	%
Common Equity Tier 1 Capital (to risk-weighted assets)
FB Financial Corporation	$	572,410	11.1	%	$	360,979	7.0	%	N/A		N/A
FirstBank	592,293		11.5	%	360,526		7.0	%	$	334,774	6.5	%