Consolidated statements of comprehensive income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Statement of Comprehensive Income [Abstract]
Net income	$ 43,302	$ 22,873	$ 96,176	$ 23,618
Other comprehensive income (loss), net of tax:
Net change in unrealized gain in available-for-sale securities, net of tax expenses (benefits) of $798, $429, $(2,654) and $4,704	2,286	1,209	(9,562)	13,303
Reclassification adjustment for gain on sale of securities included in net income, net of tax expenses of $2, $0, $4 and $0	(6)	0	(11)	0
Net change in unrealized loss in hedging activities, net of tax expenses (benefits) of $23, $(40), $135 and $(443)	67	(112)	383	(1,257)
Reclassification adjustment for gain on hedging activities, net of tax expenses of $0, $52, $0 and $104	0	(148)	0	(295)
Total other comprehensive income (loss), net of tax	2,347	949	(9,190)	11,751
Comprehensive income	45,649	23,822	86,986	35,369
Comprehensive income applicable to noncontrolling interests	8	0	8	0
Comprehensive income applicable to FB Financial Corporation	$ 45,641	$ 23,822	$ 86,978	$ 35,369