v3.25.2
Summary of Business Segment Information (Detail) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Jun. 30, 2025
Jun. 30, 2024
Dec. 31, 2024
Revenues:          
Gross written premiums $ 106,801 $ 100,706 $ 205,476 $ 194,194  
Net written premiums 103,914 97,751 199,778 189,836  
Net earned premiums 95,146 92,814 188,462 189,393  
Net losses and loss adjustment expenses 52,948 53,662 119,686 107,046  
Net investment income 14,707 15,311 29,489 29,831  
Net realized investment gains 127 205 263 1,052  
Total revenues 110,520 108,687 219,171 220,978  
Corporate expenses (7,528) (6,383) (17,028) (12,756)  
Income before income taxes 13,129 12,674 8,035 26,939  
Income tax expense 2,785 2,581 1,680 5,480  
Net income 10,344 10,093 6,355 21,459  
Total assets 1,720,585 1,738,549 1,720,585 1,738,549 $ 1,731,253
Segment assets          
Revenues:          
Gross written premiums 106,801 100,706 205,476 194,194  
Net written premiums 103,914 97,751 199,778 189,836  
Net earned premiums 95,146 92,814 188,462 189,393  
Commission and service fee income 0 [1] 0 0 [2] 0  
Policy and installment fee income 540 357 957 702  
Total segment revenues 95,686 93,171 189,419 190,095  
Net losses and loss adjustment expenses 52,948 [3] 53,662 [4] 119,686 [5] 107,046 [6]  
Net commission expenses 21,843 [3] 21,683 [4] 44,177 [5] 45,106 [6]  
Other underwriting expenses 15,072 [3],[7] 14,285 [4],[8] 30,245 [5],[9] 29,131 [6],[10]  
Income (loss) from segments 5,823 3,541 (4,689) [5] 8,812 [6]  
Total assets 254,257 261,381 254,257 261,381  
Corporate assets          
Revenues:          
Net investment income 14,707 15,311 29,489 29,831  
Net realized investment gains 127 205 263 1,052  
Total assets 1,466,328 1,477,168 1,466,328 1,477,168  
Elimination          
Revenues:          
Gross written premiums 0 0 0 0  
Net written premiums 0 0 0 0  
Net earned premiums 0   0 0  
Commission and service fee income (14,851) [1] 0 (28,900) [2] 0  
Policy and installment fee income 0 0 0 0  
Total segment revenues (14,851) 0 (28,900) 0  
Net losses and loss adjustment expenses (332) [3] 0 [4] (665) [5] 0 [6]  
Net commission expenses (11,456) [3] 0 [4] (22,027) [5] 0 [6]  
Other underwriting expenses (3,063) [3],[7] 0 [4],[8] (6,208) [5],[9] 0 [6],[10]  
Income (loss) from segments 0 [3] 0 [4] 0 [5] 0 [6]  
Total assets (19,644) 0 (19,644) 0  
Agency and Insurance Services | Segment assets          
Revenues:          
Gross written premiums 0 0 0 0  
Net written premiums 0 0 0 0  
Net earned premiums 0 0 0 0  
Commission and service fee income 14,851 [1] 0 28,900 [2] 0  
Policy and installment fee income 499 0 886 0  
Total segment revenues 15,350 0 29,786 0  
Net losses and loss adjustment expenses 0 [3] 0 [4] 0 [5] 0 [6]  
Net commission expenses 0 [3] 0 [4] 0 [5] 0 [6]  
Other underwriting expenses 13,042 [3],[7] 0 [4],[8] 25,674 [5],[9] 0 [6],[10]  
Income (loss) from segments 2,308 0 [4] 4,112 [5] 0 [6]  
Total assets 33,730 0 33,730 0  
Belmont Core | Segment assets          
Revenues:          
Gross written premiums 109,819 100,552 208,208 194,600  
Net written premiums 106,873 97,602 202,507 190,198  
Net earned premiums 97,513 89,353 189,773 178,485  
Commission and service fee income 0 [1] 0 0 [2] 0  
Policy and installment fee income 0 344 0 683  
Total segment revenues 97,513 89,697 189,773 179,168  
Net losses and loss adjustment expenses 56,109 [3] 51,126 [4] 122,561 [5] 100,035 [6]  
Net commission expenses 34,079 [3] 20,589 [4] 66,483 [5] 41,480 [6]  
Other underwriting expenses 4,591 [3],[7] 13,309 [4],[8] 9,577 [5],[9] 27,345 [6],[10]  
Income (loss) from segments 2,734 4,673 [4] (8,848) [5] 10,308 [6]  
Total assets 154,811 152,534 154,811 152,534  
Belmont Non-Core | Segment assets          
Revenues:          
Gross written premiums (3,018) 154 (2,732) (406)  
Net written premiums (2,959) 149 (2,729) (362)  
Net earned premiums (2,367) 3,461 (1,311) 10,908  
Commission and service fee income 0 [1] 0 0 [2] 0  
Policy and installment fee income 41 13 71 19  
Total segment revenues (2,326) 3,474 (1,240) 10,927  
Net losses and loss adjustment expenses (2,829) [3] 2,536 [4] (2,210) [5] 7,011 [6]  
Net commission expenses (780) [3] 1,094 [4] (279) [5] 3,626 [6]  
Other underwriting expenses 502 [3],[7] 976 [4],[8] 1,202 [5],[9] 1,786 [6],[10]  
Income (loss) from segments 781 [3] (1,132) 47 [5] (1,496) [6]  
Total assets $ 85,360 $ 108,847 $ 85,360 $ 108,847  
[1] Consists of intersegment revenues, which are eliminated in consolidation.
[2] Consists of intersegment revenues, 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] The significant expense categories and amounts align with the segment-level information that is regularly provided to the CODM.
[6] The significant expense categories and amounts align with the segment-level information that is regularly provided to the CODM.
[7] Other underwriting expenses consist primarily of personnel expenses and general operating expenses related to underwriting activities.
[8] Other underwriting expenses consist primarily of personnel expenses and general operating expenses related to underwriting activities.
[9] Other underwriting expenses consist primarily of personnel expenses and general operating expenses related to underwriting activities
[10] Other underwriting expenses consist primarily of personnel expenses and general operating expenses related to underwriting activities.