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Segment Information - Summary of Operating Results by Segment (Details) $ in Thousands | 3 Months Ended
--- | ---
Mar. 31, 2024 USD ($) State Subsidiary segment | Mar. 31, 2023 USD ($)
Segment Reporting [Abstract] |  |
Number of insurance companies | Subsidiary | 12 |
Number of states in which company operates | State | 11 |
Number of reportable segments | segment | 1 |
Segment Reporting Information [Line Items] |  |
Net premiums earned | $ 1,166,679 | $ 1,004,704
Losses and loss adjustment expenses | 903,965 | 929,529
Underwriting expenses | 273,100 | 234,300
Underwriting gain (loss) | (10,400) | (159,100)
Net investment income | 65,018 | 51,973
Net realized investment gains | 38,192 | 49,008
Other income | 4,196 | 894
Interest expense | (7,773) | (4,931)
Pre-tax income (loss) | 89,220 | (62,078)
Net income (loss) | 73,462 | (45,288)
Property & Casualty |  |
Segment Reporting Information [Line Items] |  |
Net premiums earned | 1,159,369 | 997,562
Losses and loss adjustment expenses | 900,000 | 925,800
Underwriting expenses | 269,300 | 230,800
Underwriting gain (loss) | (9,900) | (159,000)
Other |  |
Segment Reporting Information [Line Items] |  |
Net premiums earned | 7,300 | 7,100
Losses and loss adjustment expenses | 4,000 | 3,700
Underwriting expenses | 3,800 | 3,500
Underwriting gain (loss) | $ (500) | $ (100)

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- Definition The difference between the price paid by the public and the contract price less the related expenses. A broker-dealer may underwrite a security offering by contracting to buy the issue either at a fixed price or a price based on selling the offering on a best-effort basis. + References No definition available. + Details
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