Parent Company Financial Statements - Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
ASSETS
Cash and cash equivalents	$ 1,027,052	$ 1,797,740
Other assets	227,956	172,236
Goodwill	242,561	242,561	$ 242,561
Total assets	12,847,756	12,597,686	$ 11,207,330
LIABILITIES
Borrowings	415,677	171,778
Accrued expenses and other liabilities	180,973	109,949
Total liabilities	11,522,238	11,164,991
SHAREHOLDERS' EQUITY
Common stock	46,738	47,549
Additional paid-in capital	861,588	892,529
Retained earnings	586,532	486,666
Accumulated other comprehensive income	(169,433)	5,858
Total FB Financial Corporation common shareholders' equity	1,325,425	1,432,602
Total liabilities and shareholders' equity	12,847,756	12,597,686
Parent Company
ASSETS
Cash and cash equivalents	3,052	21,515
Investments in subsidiaries	1,337,657	1,427,784
Other assets	16,654	14,487
Goodwill	29	29
Total assets	1,357,392	1,463,815
LIABILITIES
Borrowings	30,930	30,930
Accrued expenses and other liabilities	1,037	283
Total liabilities	31,967	31,213
SHAREHOLDERS' EQUITY
Common stock	46,738	47,549
Additional paid-in capital	861,588	892,529
Retained earnings	586,532	486,666
Accumulated other comprehensive income	(169,433)	5,858
Total FB Financial Corporation common shareholders' equity	1,325,425	1,432,602
Total liabilities and shareholders' equity	$ 1,357,392	$ 1,463,815