Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Cash flows from operating activities:
Net income attributable to FB Financial Corporation and noncontrolling interest	$ 124,571	$ 190,301	$ 63,629
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization of fixed assets and software	8,017	8,416	7,536
Amortization of core deposit and other intangibles	4,585	5,473	5,323
Capitalization of mortgage servicing rights	(20,809)	(39,018)	(47,025)
Net change in fair value of mortgage servicing rights	(32,044)	3,503	47,660
Stock-based compensation expense	9,857	10,282	10,214
Provision for credit losses	10,393	(38,995)	94,606
Provision for credit losses on unfunded commitments	8,589	(1,998)	13,361
Provision for mortgage loan repurchases	(2,989)	(766)	2,607
Amortization of premiums and accretion of discounts on acquired loans, net	1,020	853	(3,788)
Amortization of premiums and accretion of discounts on securities, net	6,589	8,777	7,382
Loss (gain) from securities, net	376	(324)	(1,631)
Originations of loans held for sale	(2,403,476)	(6,300,892)	(6,650,258)
Repurchases of loans held for sale	(194)	(487)	0
Proceeds from sale of loans held for sale	3,067,204	6,387,110	6,487,809
Gain on sale and change in fair value of loans held for sale	(47,783)	(161,964)	(270,802)
Net loss (gain) or write-downs of other real estate owned	114	(2,504)	1,491
Loss (gain) on other assets	151	(323)	90
Provision for deferred income taxes	12,552	30,770	(25,530)
Earnings on bank-owned life insurance	(1,452)	(1,542)	(1,556)
Changes in:
Operating leases	5,030	(969)	2,664
Other assets and interest receivable	(17,222)	59,283	(57,316)
Accrued expenses and other liabilities	56,247	(100,108)	43,532
Net cash provided by (used in) operating activities	789,326	54,878	(270,002)
Activity in available-for-sale securities:
Sales	1,218	8,855	146,494
Maturities, prepayments and calls	204,748	296,256	220,549
Purchases	(242,889)	(847,212)	(424,971)
Net change in loans	(1,719,652)	(457,042)	4,383
Net change in commercial loans held for sale	43,676	147,276	114,031
Sales of FHLB stock	0	4,294	0
Purchases of FHLB stock	(26,424)	(5,279)	(515)
Purchases of premises and equipment	(10,629)	(6,102)	(5,934)
Proceeds from the sale of premises and equipment	875	0	0
Proceeds from the sale of other real estate owned and other assets	4,959	9,396	6,937
Proceeds from bank-owned life insurance	0	0	715
Net cash acquired in business combinations	0	0	248,447
Net cash (used in) provided by investing activities	(1,744,118)	(849,558)	310,136
Cash flows from financing activities:
Net (decrease) increase in demand deposits	(262,109)	1,685,033	1,519,868
Net increase (decrease) in time deposits	290,893	(306,173)	(328,035)
Net increase in securities sold under agreements to repurchase and federal funds purchased	46,229	8,517	5,262
Payments on FHLB advances	0	0	(250,000)
Net increase in short-term FHLB advances	175,000	0	0
Issuance of subordinated debt, net of issuance costs	0	0	98,189
Payments on subordinated debt	0	(60,000)	0
(Payments on) proceeds from other borrowings	0	(15,000)	15,000
Share based compensation withholding payments	(2,842)	(10,158)	(1,510)
Net proceeds from sale of common stock under employee stock purchase program	1,212	1,480	978
Repurchase of common stock	(39,979)	(7,595)	0
Dividends paid on common stock	(24,503)	(20,866)	(14,177)
Dividend equivalent payments made upon vesting of equity compensation	(168)	(717)	(87)
Noncontrolling interest distribution	(16)	(16)	(8)
Net cash provided by financing activities	184,104	1,274,522	1,045,083
Net change in cash and cash equivalents	(770,688)	479,842	1,085,217
Cash and cash equivalents at beginning of the period	1,797,740	1,317,898	232,681
Cash and cash equivalents at end of the period	1,027,052	1,797,740	1,317,898
Supplemental cash flow information:
Interest paid	63,701	41,238	48,679
Taxes paid	906	61,693	20,419
Supplemental noncash disclosures:
Transfers from loans to other real estate owned	1,437	5,262	2,746
Transfers from other real estate owned to premises and equipment	351	0	841
Loans provided for sales of other real estate owned	0	704	305
Transfers from loans to loans held for sale	46,364	10,408	11,483
Transfers from loans held for sale to loans	24,479	86,315	55,766
Rebooked GNMA loans under optional repurchase program	26,211	0	0
Stock consideration paid in business combination	0	0	480,867
Dividends declared not paid on restricted stock units	222	400	238
Decrease to retained earnings for adoption of ASU 2016-13	0	0	25,018
Right-of-use assets obtained in exchange for operating lease liabilities	$ 25,399	$ 970	$ 2,393