v3.26.1
Summary of Business Segment Information (Detail) - USD ($)
$ in Thousands
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Dec. 31, 2025
Revenues:      
Gross written premiums $ 96,450 $ 98,675  
Net written premiums 92,568 95,864  
Net earned premiums 98,355 93,316  
Net losses and loss adjustment expenses 53,861 66,738  
Net investment income 12,218 14,782  
Net realized investment gains (losses) (2,243) 136  
Total revenues 109,177 108,651  
Corporate expenses (9,038) (9,500)  
Income (loss) before income taxes 5,515 (5,094)  
Income tax expense (benefit) 1,269 (1,105)  
Net income (loss) 4,246 (3,989)  
Total assets 1,680,116 1,713,606 $ 1,720,762
Segment assets      
Revenues:      
Gross written premiums 96,450 98,675  
Net written premiums 92,568 95,864  
Net earned premiums 98,355 93,316  
Commission and service fee income 388 [1] 0 [2]  
Policy and installment fee income 459 417  
Total segment revenues 99,202 93,733  
Net losses and loss adjustment expenses 53,861 [3] 66,738 [4]  
Net commission expenses 23,338 [3] 22,334 [4]  
Other operating expenses 17,425 [3],[5] 15,173 [4],[6]  
Income (loss) from segments 4,578 [3] (10,512) [4]  
Total assets 258,770 251,933  
Corporate assets      
Revenues:      
Net investment income 12,218 14,782  
Net realized investment gains (losses) (2,243) 136  
Total assets 1,421,346 1,461,673  
Elimination      
Revenues:      
Gross written premiums 0 0  
Net written premiums 0 0  
Net earned premiums 0    
Commission and service fee income (12,390) [1] (14,049) [2]  
Policy and installment fee income (0) 0  
Total segment revenues (12,390) (14,049)  
Net losses and loss adjustment expenses (441) [3] (333) [4]  
Net commission expenses (9,524) [3] (10,571) [4]  
Other operating expenses (2,425) [3],[5] (3,145) [4],[6]  
Income (loss) from segments 0 [3] 0 [4]  
Total assets (16,106) (29,871)  
Agency and Insurance Services | Segment assets      
Revenues:      
Gross written premiums 0 0  
Net written premiums 0 0  
Net earned premiums 0 0  
Commission and service fee income 12,778 [1] 14,049 [2]  
Policy and installment fee income 461 387  
Total segment revenues 13,239 14,436  
Net losses and loss adjustment expenses 0 [3] 0 [4]  
Net commission expenses 0 [3] 0 [4]  
Other operating expenses 13,633 [3],[5] 12,632 [4],[6]  
Income (loss) from segments (394) [3] 1,804 [4]  
Total assets 44,924 41,886  
Belmont Core | Segment assets      
Revenues:      
Gross written premiums 96,507 98,389  
Net written premiums 92,625 95,634  
Net earned premiums 98,371 92,260  
Commission and service fee income 0 [1] 0 [2]  
Policy and installment fee income 0 0  
Total segment revenues 98,371 92,260  
Net losses and loss adjustment expenses 54,304 [3] 66,452 [4]  
Net commission expenses 32,695 [3] 32,404 [4]  
Other operating expenses 6,130 [3],[5] 4,986 [4],[6]  
Income (loss) from segments 5,242 [3] (11,582) [4]  
Total assets 154,957 153,788  
Belmont Non-Core | Segment assets      
Revenues:      
Gross written premiums (57) 286  
Net written premiums (57) 230  
Net earned premiums (16) 1,056  
Commission and service fee income 0 [1] 0 [2]  
Policy and installment fee income (2) 30  
Total segment revenues (18) 1,086  
Net losses and loss adjustment expenses (2) [3] 619 [4]  
Net commission expenses 167 [3] 501 [4]  
Other operating expenses 87 [3],[5] 700 [4],[6]  
Income (loss) from segments (270) [3] (734) [4]  
Total assets $ 74,995 $ 86,130  
[1] Consists of intersegment revenues of $12.4 million, which are eliminated in consolidation, and third party commission and service fee income of $0.4 million in 2026.
[2] Consists of intersegment revenues of $14.0 million, which are eliminated in consolidation.
[3] The significant expense categories and amounts align with the segment-level information that is regularly provided to the CODM.
[4] The significant expense categories and amounts align with the segment-level information that is regularly provided to the CODM.
[5] Other operating expenses consist primarily of personnel expenses and general operating expenses related to underwriting and distribution activities.
[6] Other operating expenses consist primarily of personnel expenses and general operating expenses related to underwriting activities.