Parent Company Financial Statements - Schedule of Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
ASSETS
Cash and cash equivalents	$ 1,042,488	$ 810,932
Other assets	233,288	203,409
Goodwill	242,561	242,561	$ 242,561
Total assets	13,157,482	12,604,403	$ 12,847,756
LIABILITIES
Borrowings	176,789	390,964
Accrued expenses and other liabilities	142,604	142,622
Total liabilities	11,589,851	11,149,516
SHAREHOLDERS’ EQUITY
Common stock	46,663	46,849
Additional paid-in capital	860,266	864,258
Retained earnings	762,293	678,412
Accumulated other comprehensive loss	(101,684)	(134,725)
Total FB Financial Corporation common shareholders’ equity	1,567,538	1,454,794
Total liabilities and shareholders’ equity	13,157,482	12,604,403
Parent Company
ASSETS
Cash and cash equivalents	32,857	21,448
Investments in subsidiaries	1,527,292	1,449,439
Other assets	38,918	15,291
Goodwill	29	29
Total assets	1,599,096	1,486,207
LIABILITIES
Borrowings	30,930	30,930
Accrued expenses and other liabilities	628	483
Total liabilities	31,558	31,413
SHAREHOLDERS’ EQUITY
Common stock	46,663	46,849
Additional paid-in capital	860,266	864,258
Retained earnings	762,293	678,412
Accumulated other comprehensive loss	(101,684)	(134,725)
Total FB Financial Corporation common shareholders’ equity	1,567,538	1,454,794
Total liabilities and shareholders’ equity	$ 1,599,096	$ 1,486,207