Consolidated statements of comprehensive income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement of Comprehensive Income [Abstract]
Net income	$ 52,874	$ 745
Other comprehensive (loss) income, net of tax:
Net change in unrealized (loss) gain in available-for-sale securities, net of taxes of $3,452 and $4,275	(11,848)	12,094
Reclassification adjustment for gain on sale of securities included in net income, net of taxes of $2 and $0	(5)	0
Net change in unrealized gain (loss) in hedging activities, net of taxes of $112 and $403	316	(1,145)
Reclassification adjustment for gain on hedging activities, net of taxes of $— and $52	0	(147)
Total other comprehensive (loss) income , net of tax	(11,537)	10,802
Comprehensive income	41,337	11,547
Comprehensive income applicable to noncontrolling interests	0	0
Comprehensive income applicable to FB Financial Corporation	$ 41,337	$ 11,547