Consolidated Statements of Changes in Shareholders' Equity - USD ($) $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Adjusted balance	FNB Financial Corp.	Franklin Financial Network, Inc.	Total common shareholders' equity	Total common shareholders' equity Cumulative Effect, Period of Adoption, Adjustment	Total common shareholders' equity Adjusted balance	Total common shareholders' equity FNB Financial Corp.	Total common shareholders' equity Franklin Financial Network, Inc.	Common stock	Common stock Adjusted balance	Common stock FNB Financial Corp.	Common stock Franklin Financial Network, Inc.	Additional paid-in capital	Additional paid-in capital Adjusted balance	Additional paid-in capital FNB Financial Corp.	Additional paid-in capital Franklin Financial Network, Inc.	Retained earnings	Retained earnings Cumulative Effect, Period of Adoption, Adjustment	Retained earnings Adjusted balance	Accumulated other comprehensive income (loss), net	Accumulated other comprehensive income (loss), net Adjusted balance	Noncontrolling interest	Noncontrolling interest Adjusted balance	Noncontrolling interest Franklin Financial Network, Inc.
Beginning balance at Dec. 31, 2019	$ 762,329	$ (25,018)	$ 737,311			$ 762,329	$ (25,018)	$ 737,311			$ 31,034	$ 31,034			$ 425,633	$ 425,633			$ 293,524	$ (25,018)	$ 268,506	$ 12,138	$ 12,138	$ 0	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to FB Financial Corporation and noncontrolling interest	63,629					63,621													63,621					8
Other comprehensive income (loss), net of taxes	15,457					15,457																15,457
Common stock issued in connection with acquisitions, net of registration costs (See Note 2)				$ 34,847	$ 444,966				$ 34,847	$ 444,873			$ 955	$ 15,058			$ 33,892	$ 429,815								$ 93
Stock based compensation expense	10,214					10,214					22				10,192
Restricted stock units vested and distributed, net of shares withheld	(1,510)					(1,510)					123				(1,633)
Shares issued under employee stock purchase program	978					978					30				948
Dividends declared	(14,502)					(14,502)													(14,502)
Noncontrolling interest distribution	(8)																							(8)
Ending 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	190,301					190,285													190,285					16
Other comprehensive income (loss), net of taxes	(21,737)					(21,737)																(21,737)
Repurchase of common stock	(7,595)					(7,595)					(179)				(7,416)
Stock based compensation expense	10,282					10,282					7				10,275
Restricted stock units vested and distributed, net of shares withheld	(10,158)					(10,158)					462				(10,620)
Shares issued under employee stock purchase program	1,480					1,480					37				1,443
Dividends declared	(21,244)					(21,244)													(21,244)
Noncontrolling interest distribution	(16)																							(16)
Ending 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	124,571					124,555													124,555					16
Other comprehensive income (loss), net of taxes	(175,291)					(175,291)																(175,291)
Repurchase of common stock	(39,979)					(39,979)					(997)				(38,982)
Stock based compensation expense	9,857					9,857					3				9,854
Restricted stock units vested and distributed, net of shares withheld	(2,842)					(2,842)					156				(2,998)
Shares issued under employee stock purchase program	1,212					1,212					27				1,185
Dividends declared	(24,689)					(24,689)													(24,689)
Noncontrolling interest distribution	(16)																							(16)
Ending balance at Dec. 31, 2022	$ 1,325,518					$ 1,325,425					$ 46,738				$ 861,588				$ 586,532			$ (169,433)		$ 93