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Summary Of Investments Other Than Investments In Related Parties (Details) - USD ($) $ in Thousands | Dec. 31, 2024 | Dec. 31, 2023
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SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items] |  |
Cost | $ 6,061,318 | $ 5,229,297
Fair Value | 6,076,370 | 5,228,520
Amounts in the Balance Sheet | 6,076,370 | 5,228,520
Fixed maturity securities |  |
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items] |  |
Cost | 4,982,458 | 4,394,983
Fair Value | 4,913,378 | 4,319,336
Amounts in the Balance Sheet | 4,913,378 | 4,319,336
U.S. government bonds and agencies |  |
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items] |  |
Cost | 94,102 | 174,903
Fair Value | 93,837 | 174,450
Amounts in the Balance Sheet | 93,837 | 174,450
Municipal securities |  |
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items] |  |
Cost | 3,018,428 | 2,797,971
Fair Value | 2,987,054 | 2,777,258
Amounts in the Balance Sheet | 2,987,054 | 2,777,258
Mortgage-backed securities |  |
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items] |  |
Cost | 271,444 | 201,727
Fair Value | 259,421 | 186,887
Amounts in the Balance Sheet | 259,421 | 186,887
Corporate securities |  |
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items] |  |
Cost | 863,323 | 626,723
Fair Value | 841,715 | 599,630
Amounts in the Balance Sheet | 841,715 | 599,630
Collateralized loan obligations |  |
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items] |  |
Cost | 623,817 | 486,984
Fair Value | 626,255 | 484,947
Amounts in the Balance Sheet | 626,255 | 484,947
Other asset-backed securities |  |
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items] |  |
Cost | 111,344 | 106,675
Fair Value | 105,096 | 96,164
Amounts in the Balance Sheet | 105,096 | 96,164
Equity securities |  |
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items] |  |
Cost | 795,068 | 654,939
Fair Value | 879,175 | 730,693
Amounts in the Balance Sheet | 879,175 | 730,693
Common stock |  |
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items] |  |
Cost | 634,821 | 497,543
Fair Value | 741,369 | 597,888
Amounts in the Balance Sheet | 741,369 | 597,888
Non-redeemable preferred stock |  |
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items] |  |
Cost | 52,206 | 64,860
Fair Value | 42,603 | 51,563
Amounts in the Balance Sheet | 42,603 | 51,563
Private equity funds measured at net asset value |  |
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items] |  |
Cost | 108,041 | 92,536
Fair Value | 95,203 | 81,242
Amounts in the Balance Sheet | 95,203 | 81,242
Short-term investments |  |
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items] |  |
Cost | 283,792 | 179,375
Fair Value | 283,817 | 178,491
Amounts in the Balance Sheet | $ 283,817 | $ 178,491

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