v3.26.1
Segment Reporting - Schedule of Segment Financial Information (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Dec. 31, 2025
Segment Reporting [Line Items]          
Interest income $ 229,438 $ 182,084 $ 454,788 $ 361,790  
Interest expense 80,466 70,669 159,851 142,734  
Net interest income 148,972 111,415 294,937 219,056  
Provisions for credit losses 10,116 5,337 13,140 7,629  
Net interest income after provision for credit losses 138,856 106,078 281,797 211,427  
Mortgage banking income 11,170 13,029 23,423 25,455  
Other noninterest (loss) income 14,610 (47,581) 28,732 (36,975)  
Total noninterest income 25,780 (34,552) 52,155 (11,520)  
Salaries, commissions and employee benefits 53,332 46,631 110,680 94,982  
Merger and integration costs 0 2,734 1,447 3,135  
Depreciation and amortization 3,079 2,868 6,222 5,635  
Amortization of intangibles 1,804 631 3,673 1,287  
Other noninterest expense 33,265 28,397 64,622 55,771  
Total noninterest expense 91,480 81,261 186,644 160,810  
Income (loss) before income taxes 73,156 (9,735) 147,308 39,097  
Income tax expense (benefit) 14,499 (12,652) 31,125 (3,181)  
Net income applicable to FB Financial Corporation and noncontrolling interest 58,657 2,917 116,183 42,278  
Net income applicable to noncontrolling interest 8 8 8 8  
Net income applicable to FB Financial Corporation 58,649 2,909 116,175 42,270  
Total assets 16,796,101 13,354,238 16,796,101 13,354,238 $ 16,300,292
Goodwill 350,353 242,561 350,353 242,561 $ 350,353
Banking          
Segment Reporting [Line Items]          
Interest income 226,981 180,960 450,399 359,875  
Interest expense 81,549 72,051 161,845 145,207  
Net interest income 145,432 108,909 288,554 214,668  
Provisions for credit losses 9,139 582 11,126 2,771  
Net interest income after provision for credit losses 136,293 108,327 277,428 211,897  
Mortgage banking income 0 0 0 0  
Other noninterest (loss) income 14,403 (47,720) 28,365 (37,060)  
Total noninterest income 14,403 (47,720) 28,365 (37,060)  
Salaries, commissions and employee benefits 46,517 38,635 95,881 80,104  
Merger and integration costs   2,734 1,447 3,135  
Depreciation and amortization 3,070 2,849 6,201 5,592  
Amortization of intangibles 1,804 631 3,673 1,287  
Other noninterest expense 27,728 22,481 53,493 44,121  
Total noninterest expense 79,119 67,330 160,695 134,239  
Income (loss) before income taxes 71,577 (6,723) 145,098 40,598  
Total assets 16,015,694 12,736,830 16,015,694 12,736,830  
Goodwill 350,353 242,561 350,353 242,561  
Mortgage          
Segment Reporting [Line Items]          
Interest income 2,457 1,124 4,389 1,915  
Interest expense (1,083) (1,382) (1,994) (2,473)  
Net interest income 3,540 2,506 6,383 4,388  
Provisions for credit losses 977 4,755 2,014 4,858  
Net interest income after provision for credit losses 2,563 (2,249) 4,369 (470)  
Mortgage banking income 11,170 13,029 23,423 25,455  
Other noninterest (loss) income 207 139 367 85  
Total noninterest income 11,377 13,168 23,790 25,540  
Salaries, commissions and employee benefits 6,815 7,996 14,799 14,878  
Merger and integration costs   0 0 0  
Depreciation and amortization 9 19 21 43  
Amortization of intangibles 0 0 0 0  
Other noninterest expense 5,537 5,916 11,129 11,650  
Total noninterest expense 12,361 13,931 25,949 26,571  
Income (loss) before income taxes 1,579 (3,012) 2,210 (1,501)  
Total assets 780,407 617,408 780,407 617,408  
Goodwill $ 0 $ 0 $ 0 $ 0