v3.26.3
Segment Reporting - Schedule of Segment Financial Information (Details) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Sep. 30, 2026
Sep. 30, 2025
Sep. 30, 2026
Sep. 30, 2025
Dec. 31, 2025
Segment Reporting [Line Items]          
Interest income $ 236,107 $ 236,898 $ 690,895 $ 598,688  
Interest expense 86,161 89,658 246,012 232,392  
Net interest income 149,946 147,240 444,883 366,296  
Provisions for credit losses 1,424 34,417 14,564 42,046  
Net interest income after provision for credit losses 148,522 112,823 430,319 324,250  
Mortgage banking income 9,425 13,484 32,848 38,939  
Other noninterest income 15,115 13,151 43,847 (23,824)  
Total noninterest income 24,540 26,635 76,695 15,115  
Salaries, commissions and employee benefits 56,054 59,210 166,734 154,192  
Merger and integration costs 0 16,057 1,447 19,192  
Depreciation and amortization 3,113 3,185 9,335 8,820  
Amortization of intangibles 1,741 2,079 5,414 3,366  
Other noninterest expense 35,126 29,325 99,748 85,096  
Total noninterest expense 96,034 109,856 282,678 270,666  
Income before income taxes 77,028 29,602 224,336 68,699  
Income tax expense 16,826 6,227 47,951 3,046  
Net income attributable to FB Financial Corporation and noncontrolling interest 60,202 23,375 176,385 65,653  
Net income attributable to noncontrolling interest 0 0 8 8  
Net income attributable to FB Financial Corporation 60,202 23,375 176,377 65,645  
Total assets 17,093,991 16,236,459 17,093,991 16,236,459 $ 16,300,292
Goodwill 350,353 350,353 350,353 350,353 $ 350,353
Banking          
Segment Reporting [Line Items]          
Interest income 233,558 236,073 683,957 595,948  
Interest expense 87,434 91,214 249,279 236,421  
Net interest income 146,124 144,859 434,678 359,527  
Provisions for credit losses 981 34,070 12,107 36,841  
Net interest income after provision for credit losses 145,143 110,789 422,571 322,686  
Mortgage banking income 0 0 0 0  
Other noninterest income 15,027 13,078 43,392 (23,982)  
Total noninterest income 15,027 13,078 43,392 (23,982)  
Salaries, commissions and employee benefits 48,912 51,441 144,793 131,545  
Merger and integration costs   16,057 1,447 19,192  
Depreciation and amortization 3,103 3,167 9,304 8,759  
Amortization of intangibles 1,741 2,079 5,414 3,366  
Other noninterest expense 28,731 24,225 82,224 68,346  
Total noninterest expense 82,487 96,969 243,182 231,208  
Income before income taxes 77,683 26,898 222,781 67,496  
Total assets 16,232,445 15,598,629 16,232,445 15,598,629  
Goodwill 350,353 350,353 350,353 350,353  
Mortgage          
Segment Reporting [Line Items]          
Interest income 2,549 825 6,938 2,740  
Interest expense (1,273) (1,556) (3,267) (4,029)  
Net interest income 3,822 2,381 10,205 6,769  
Provisions for credit losses 443 347 2,457 5,205  
Net interest income after provision for credit losses 3,379 2,034 7,748 1,564  
Mortgage banking income 9,425 13,484 32,848 38,939  
Other noninterest income 88 73 455 158  
Total noninterest income 9,513 13,557 33,303 39,097  
Salaries, commissions and employee benefits 7,142 7,769 21,941 22,647  
Merger and integration costs   0 0 0  
Depreciation and amortization 10 18 31 61  
Amortization of intangibles 0 0 0 0  
Other noninterest expense 6,395 5,100 17,524 16,750  
Total noninterest expense 13,547 12,887 39,496 39,458  
Income before income taxes (655) 2,704 1,555 1,203  
Total assets 861,546 637,830 861,546 637,830  
Goodwill $ 0 $ 0 $ 0 $ 0