Consolidated Statements of Changes in Shareholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Total common shareholders' equity	Common stock	Additional paid-in capital	Retained earnings	Accumulated other comprehensive loss, net	Noncontrolling interest
Beginning balance at Dec. 31, 2020	$ 1,291,382	$ 1,291,289	$ 47,222	$ 898,847	$ 317,625	$ 27,595	$ 93
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to FB Financial Corporation and noncontrolling interest	141,466	141,458			141,458		8
Other comprehensive income (loss), net of taxes	(14,958)	(14,958)				(14,958)
Repurchase of common stock	(436)	(436)	(11)	(425)
Stock based compensation expense	8,065	8,065	6	8,059
Restricted stock units vested and distributed, net of shares withheld	(10,042)	(10,042)	454	(10,496)
Shares issued under employee stock purchase program	1,480	1,480	37	1,443
Dividends declared	(15,943)	(15,943)			(15,943)
Noncontrolling interest distribution	(8)						(8)
Ending balance at Sep. 30, 2021	1,401,006	1,400,913	47,708	897,428	443,140	12,637	93
Beginning balance at Jun. 30, 2021	1,371,814	1,371,721	47,361	902,782	403,173	18,405	93
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to FB Financial Corporation and noncontrolling interest	45,290	45,290			45,290		0
Other comprehensive income (loss), net of taxes	(5,768)	(5,768)				(5,768)
Repurchase of common stock	(436)	(436)	(11)	(425)
Stock based compensation expense	2,884	2,884	1	2,883
Restricted stock units vested and distributed, net of shares withheld	(8,102)	(8,102)	342	(8,444)
Shares issued under employee stock purchase program	647	647	15	632
Dividends declared	(5,323)	(5,323)			(5,323)
Ending balance at Sep. 30, 2021	1,401,006	1,400,913	47,708	897,428	443,140	12,637	93
Beginning balance at Dec. 31, 2021	1,432,695	1,432,602	47,549	892,529	486,666	5,858	93
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to FB Financial Corporation and noncontrolling interest	86,420	86,412			86,412		8
Other comprehensive income (loss), net of taxes	(193,298)	(193,298)				(193,298)
Repurchase of common stock	(32,743)	(32,743)	(795)	(31,948)
Stock based compensation expense	8,153	8,153	3	8,150
Restricted stock units vested and distributed, net of shares withheld	(2,635)	(2,635)	142	(2,777)
Shares issued under employee stock purchase program	1,212	1,212	27	1,185
Dividends declared	(18,542)	(18,542)			(18,542)
Noncontrolling interest distribution	(8)						(8)
Ending balance at Sep. 30, 2022	1,281,254	1,281,161	46,926	867,139	554,536	(187,440)	93
Beginning balance at Jun. 30, 2022	1,319,945	1,319,852	46,882	864,614	528,851	(120,495)	93
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to FB Financial Corporation and noncontrolling interest	31,831	31,831			31,831		0
Other comprehensive income (loss), net of taxes	(66,945)	(66,945)				(66,945)
Stock based compensation expense	2,533	2,533	1	2,532
Restricted stock units vested and distributed, net of shares withheld	(489)	(489)	31	(520)
Shares issued under employee stock purchase program	525	525	12	513
Dividends declared	(6,146)	(6,146)			(6,146)
Ending balance at Sep. 30, 2022	$ 1,281,254	$ 1,281,161	$ 46,926	$ 867,139	$ 554,536	$ (187,440)	$ 93