Parent Company Financial Statements - Schedule of Income Statements (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income
Dividend income from bank subsidiaries	$ 44,805	$ 12,258	$ 2,893
Net interest income	407,217	412,235	347,370
Expenses
Interest expense	271,193	69,187	37,628
Other noninterest expense	310,090	335,744	359,678
Net income applicable to FB Financial Corporation	120,224	124,555	190,285
Parent Company
Income
Dividend income from bank subsidiaries	49,000	49,000	122,500
Dividend income from nonbank subsidiaries	530	0	2,525
Loss on investments	0	0	249
Other income	57	89	15
Net interest income	49,587	49,089	125,289
Expenses
Interest expense	1,590	1,587	2,455
Salaries, legal and professional fees	1,461	1,590	1,445
Other noninterest expense	478	771	1,812
Total expenses	3,529	3,948	5,712
Income before income tax benefit and equity in undistributed earnings of subsidiaries	46,058	45,141	119,577
Federal and state income tax benefit	(887)	(1,002)	(2,992)
Income before equity in undistributed earnings of subsidiaries	46,945	46,143	122,569
Equity in undistributed earnings from bank subsidiaries	73,832	76,232	68,351
Equity in undistributed earnings from nonbank subsidiaries	(553)	2,180	(635)
Net income applicable to FB Financial Corporation	$ 120,224	$ 124,555	$ 190,285