Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Cash flows from operating activities:
Net income attributable to FB Financial Corporation and noncontrolling interest	$ 90,863	$ 86,420
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization of fixed assets and software	7,361	6,105
Amortization of core deposit and other intangibles	2,819	3,546
Amortization of issuance costs on subordinated debt	290	291
Capitalization of mortgage servicing rights	(6,134)	(19,523)
Net change in fair value of mortgage servicing rights	1,789	(36,392)
Stock-based compensation expense	8,317	8,153
Provision for credit losses on loans HFI	13,603	10,241
(Reversal of) provision for credit losses on unfunded commitments	(11,369)	9,197
Provision for mortgage loan repurchases	(650)	(1,989)
(Accretion) amortization of discounts and premiums on acquired loans, net	(617)	1,339
Amortization of premiums and accretion of discounts on securities, net	3,959	5,178
Loss from investment securities, net	14,156	401
Originations of loans held for sale	(970,131)	(2,129,129)
Repurchases of loans held for sale	0	(194)
Proceeds from sale of loans held for sale	1,013,584	2,796,313
Gain on sale and change in fair value of loans held for sale	(25,847)	(43,648)
Net (gain) loss on write-downs of other real estate owned and other assets	(465)	13
Provision for deferred income taxes	1,660	15,879
Earnings on bank-owned life insurance	(1,382)	(1,099)
Changes in:
Operating lease assets and liabilities, net	1,591	4,485
Other assets and interest receivable	(14,596)	(23,220)
Accrued expenses and other liabilities	7,911	51,583
Net cash provided by operating activities	136,712	743,950
Activity in available-for-sale securities:
Sales	75,857	1,218
Maturities, prepayments and calls	91,361	170,701
Purchases	(82,829)	(242,639)
Net change in loans	21,419	(1,480,809)
Sales of FHLB stock	31,825	0
Purchases of FHLB stock	(7,993)	(26,370)
Purchases of premises and equipment	(16,563)	(6,060)
Proceeds from the sale of premises and equipment	105	875
Proceeds from the sale of other real estate owned	5,692	4,753
Proceeds from the sale of other assets	1,197	4
Proceeds from bank-owned life insurance	236	0
Net cash provided by (used in) investing activities	120,307	(1,578,327)
Cash flows from financing activities:
Net decrease in deposits	(219,798)	(820,640)
Net decrease in securities sold under agreements to repurchase and federal funds purchased	(12,240)	(11,708)
Net (decrease) increase in short-term FHLB advances	(175,000)
Net (decrease) increase in short-term FHLB advances		540,000
Share based compensation withholding payments	(3,243)	(2,635)
Net proceeds from sale of common stock under employee stock purchase program	723	1,212
Repurchase of common stock	(4,944)	(32,743)
Dividends paid on common stock	(21,026)	(18,401)
Dividend equivalent payments made upon vesting of equity compensation	(217)	(150)
Noncontrolling interest distribution	(8)	(8)
Net cash used in financing activities	(435,753)	(345,073)
Net change in cash and cash equivalents	(178,734)	(1,179,450)
Cash and cash equivalents at beginning of the period	1,027,052	1,797,740
Cash and cash equivalents at end of the period	848,318	618,290
Supplemental cash flow information:
Interest paid	185,513	31,322
Taxes paid, net	37,875	808
Supplemental noncash disclosures:
Transfers from loans to other real estate owned	657	984
Transfers from loans to other assets	2,233	0
Transfers to other assets	75	0
Loans provided for sales of other assets	516	0
Transfers from loans to loans held for sale	11,351	42,997
Transfers from loans held for sale to loans	3,076	23,183
(Decrease) increase in rebooked GNMA loans under optional repurchase program	(4,137)	26,485
Trade date payable - securities	10,930	0
Trade date receivable - securities	789	0
Dividends declared not paid on restricted stock units	241	173
Right-of-use assets obtained in exchange for operating lease liabilities	$ 5,617	$ 24,605