Consolidated Statements of Changes in Shareholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	RSUs	PSUs	Total common shareholders' equity	Total common shareholders' equity RSUs	Total common shareholders' equity PSUs	Common stock	Common stock RSUs	Common stock PSUs	Additional paid-in capital	Additional paid-in capital RSUs	Additional paid-in capital PSUs	Retained earnings	Accumulated other comprehensive income (loss), net	Noncontrolling interest
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 and performance-based restricted stock units vested, net of taxes		$ (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 and performance-based restricted stock units vested, net of taxes		(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
Beginning balance at Dec. 31, 2022	1,325,518			1,325,425			46,738			861,588			586,532	(169,433)	93
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to FB Financial Corporation and noncontrolling interest	90,863			90,855									90,855		8
Other comprehensive income (loss), net of taxes	(22,965)			(22,965)										(22,965)
Repurchase of common stock	(4,944)			(4,944)			(136)			(4,808)
Stock based compensation expense	8,317			8,317			7			8,310
Restricted stock and performance-based restricted stock units vested, net of taxes		(1,928)	$ (1,315)		(1,928)	$ (1,315)		141	$ 68		(2,069)	$ (1,383)
Shares issued under employee stock purchase program	723			723			21			702
Dividends declared	(21,267)			(21,267)									(21,267)
Noncontrolling interest distribution	(8)														(8)
Ending balance at Sep. 30, 2023	1,372,994			1,372,901			46,839			862,340			656,120	(192,398)	93
Beginning balance at Jun. 30, 2023	1,387,044			1,386,951			46,799			859,516			644,043	(163,407)	93
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to FB Financial Corporation and noncontrolling interest	19,175			19,175									19,175		0
Other comprehensive income (loss), net of taxes	(28,991)			(28,991)										(28,991)
Stock based compensation expense	2,784			2,784			1			2,783
Restricted stock and performance-based restricted stock units vested, net of taxes		$ (322)	$ 0		$ (322)	$ 0		$ 26	$ 0		$ (348)	$ 0
Shares issued under employee stock purchase program	402			402			13			389
Dividends declared	(7,098)			(7,098)									(7,098)
Ending balance at Sep. 30, 2023	$ 1,372,994			$ 1,372,901			$ 46,839			$ 862,340			$ 656,120	$ (192,398)	$ 93