Parent Company Financial Statements - Income Statements (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income
Dividend income from bank subsidiaries	$ 12,258	$ 2,893	$ 2,705
Net interest income	412,235	347,370	265,658
Interest expense
Interest expense	69,187	37,628	48,986
Other noninterest expense	335,744	359,678	364,226
Net income applicable to FB Financial Corporation	124,555	190,285	63,621
Parent Company
Income
Dividend income from bank subsidiaries	49,000	122,500	49,706
Dividend income from nonbank subsidiaries	0	2,525	0
Gain on investments	0	249	217
Other income	89	15	1,732
Net interest income	49,089	125,289	51,655
Interest expense
Interest expense	1,587	2,455	3,122
Salaries, legal and professional fees	1,590	1,445	1,458
Other noninterest expense	771	1,812	283
Total expenses	3,948	5,712	4,863
Income before income tax benefit and equity in undistributed earnings of subsidiaries	45,141	119,577	46,792
Federal and state income tax benefit	(1,002)	(2,992)	(1,155)
Income before equity in undistributed earnings of subsidiaries	46,143	122,569	47,947
Equity in undistributed earnings from bank subsidiaries	76,232	68,351	15,168
Equity in undistributed earnings from nonbank subsidiaries	2,180	(635)	506
Net income applicable to FB Financial Corporation	$ 124,555	$ 190,285	$ 63,621