Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024
Cash flows from operating activities:
Net income attributable to FB Financial Corporation and noncontrolling interest	$ 65,653	$ 78,157
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization of fixed assets and software	8,820	8,957
Amortization of core deposit and other intangibles	3,366	2,260
Amortization of subordinated debt issuance costs and fair value premium, net	556	290
Capitalization of mortgage servicing rights	(2,498)	(4,067)
Net change in fair value of mortgage servicing rights	14,696	11,219
Stock-based compensation expense	11,567	7,261
Provision for credit losses on loans HFI	30,761	7,648
Provision for (reversal of) credit losses on unfunded commitments	11,285	(2,728)
Provision for mortgage loan repurchases	233	200
Accretion of discounts and premiums on acquired loans, net	(6,965)	(538)
(Accretion) amortization of premiums and discounts on securities, net	(2,183)	2,787
Loss from investment securities, net	60,521	56,378
Originations of loans held for sale	(1,012,802)	(913,315)
Proceeds from sale of loans held for sale	989,777	911,650
Gain on sale and change in fair value of loans held for sale	(28,780)	(26,008)
Net loss on write-downs of premises and equipment, other real estate owned and other assets	1,035	5
Provision for deferred income taxes	(4,910)	(3,895)
Equity method investment loss	1,733	0
Earnings on bank-owned life insurance	(1,589)	(3,296)
Changes in:
Operating lease assets and liabilities, net	(432)	(1,110)
Other assets and interest receivable	(8,585)	(12,170)
Accrued expenses and other liabilities	(28,210)	4,985
Net cash provided by operating activities	103,049	124,670
Activity in available-for-sale securities:
Sales	266,894	526,076
Maturities, prepayments and calls	217,865	224,070
Purchases	(289,601)	(823,976)
Proceeds from sales of equity securities	1,345	0
Net change in loans	(432,487)	(73,631)
Net purchases of FHLB stock	(6)
Net redemptions of FHLB stock		1,331
Purchases of premises and equipment	(7,215)	(4,977)
Proceeds from the sale of premises and equipment	1,850	489
Proceeds from the sale of other real estate owned	5,071	1,846
Purchase of equity method securities	0	(10,000)
Proceeds from the sale of other assets	841	898
Proceeds from bank-owned life insurance	690	7,272
Net cash acquired in business combinations	370,147	0
Net cash provided by (used in) investing activities	135,394	(150,602)
Cash flows from financing activities:
Net increase in deposits	133,991	423,427
Net increase (decrease) in securities sold under agreements to repurchase and federal funds purchased	93,987	(89,056)
Repayment of Bank Term Funding Program borrowings	0	(130,000)
Redemptions on subordinated debt	(130,930)	0
Stock-based compensation withholding payments	(2,787)	(1,787)
Net proceeds from sale of common stock under employee stock purchase program	897	882
Repurchase of common stock	(68,013)	(12,699)
Dividends paid on common stock	(27,729)	(23,847)
Dividend equivalent payments made upon vesting of equity compensation	(306)	(162)
Noncontrolling interest distribution	(8)	(8)
Net cash (used in) provided by financing activities	(898)	166,750
Net change in cash and cash equivalents	237,545	140,818
Cash and cash equivalents at beginning of the period	1,042,488	810,932
Cash and cash equivalents at end of the period	1,280,033	951,750
Supplemental cash flow information:
Interest paid	240,014	229,275
Taxes paid, net	12,393	34,173
Supplemental noncash disclosures:
Transfers from loans HFI to other real estate owned	5,272	2,400
Transfers from loans HFI to other assets	4,534	3,316
Transfers from loans HFI to loans held for sale	5,306	167
Transfers from loans held for sale to loans HFI	7,481	1,850
Loans HFI provided for sales of other assets	2,074	924
(Decrease) increase in rebooked GNMA loans under optional repurchase program	(9,697)	9,308
Stock consideration paid in business combination	368,028	0
Trade date payable - securities	25,036	0
Trade date receivable - securities	0	365
Dividends declared not paid on restricted stock units and performance stock units	309	279
Right-of-use assets obtained in exchange for operating lease liabilities	$ 6,404	$ 3,925