Parent Company Financial Statements - Schedule of Income Statements (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Income
Dividend income from bank subsidiaries	$ 44,330	$ 44,805	$ 12,258
Net interest income	416,503	407,217	412,235
Expenses
Other noninterest expense	98,173	106,649	124,253
Net income applicable to FB Financial Corporation	116,035	120,224	124,555
Parent Company
Income
Dividend income from bank subsidiaries	83,200	49,000	49,000
Dividend income from nonbank subsidiaries	0	530	0
Other income	7	57	89
Net interest income	83,207	49,587	49,089
Expenses
Interest expense	2,107	1,590	1,587
Salaries, legal and professional fees	1,549	1,461	1,590
Other noninterest expense	426	478	771
Total expenses	4,082	3,529	3,948
Income before income tax benefit and equity in undistributed earnings of subsidiaries	79,125	46,058	45,141
Federal and state income tax benefit	(1,047)	(887)	(1,002)
Income before equity in undistributed earnings of subsidiaries	80,172	46,945	46,143
Equity in undistributed earnings from bank subsidiaries	35,863	73,832	76,232
Equity in undistributed earnings from nonbank subsidiaries	0	(553)	2,180
Net income applicable to FB Financial Corporation	$ 116,035	$ 120,224	$ 124,555