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Fair Value Measurement (Schedule Of Assets And Liabilities Measured At Fair Value On A Recurring Basis Valuation Techniques) (Details) - USD ($) $ in Thousands | Jun. 30, 2025 | Dec. 31, 2024
--- | --- | ---
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Total fixed maturity securities | $ 4,993,829 | $ 4,913,378
Equity securities | 687,652 | 879,175
Notes receivable | 31,831 | 31,231
Fair Value, Measurements, Recurring |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Total fixed maturity securities | 4,993,829 | 4,913,378
Equity securities | 687,652 | 879,175
Short-term investments | 281,766 | 283,817
Notes receivable | 31,831 | 31,231
Assets, fair value disclosure | 5,995,078 | 6,107,601
Total liabilities at fair value | 1,397 | 213
Fair Value, Measurements, Recurring | Level 1 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Total fixed maturity securities | 63,680 | 75,874
Equity securities | 549,027 | 741,369
Short-term investments | 272,766 | 282,162
Notes receivable | 0 | 0
Assets, fair value disclosure | 885,473 | 1,099,405
Total liabilities at fair value | 1,397 | 213
Fair Value, Measurements, Recurring | Level 2 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Total fixed maturity securities | 4,930,149 | 4,837,504
Equity securities | 41,458 | 42,603
Short-term investments | 9,000 | 1,655
Notes receivable | 31,831 | 31,231
Assets, fair value disclosure | 5,012,438 | 4,912,993
Total liabilities at fair value | 0 | 0
Fair Value, Measurements, Recurring | Level 3 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Total fixed maturity securities | 0 | 0
Equity securities | 0 | 0
Short-term investments | 0 | 0
Notes receivable | 0 | 0
Assets, fair value disclosure | 0 | 0
Total liabilities at fair value | 0 | 0
Fair Value, Measurements, Recurring | U.S. government bonds and agencies |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Total fixed maturity securities | 63,680 | 93,837
Fair Value, Measurements, Recurring | U.S. government bonds and agencies | Level 1 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Total fixed maturity securities | 63,680 | 75,874
Fair Value, Measurements, Recurring | U.S. government bonds and agencies | Level 2 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Total fixed maturity securities | 0 | 17,963
Fair Value, Measurements, Recurring | U.S. government bonds and agencies | Level 3 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Total fixed maturity securities | 0 | 0
Fair Value, Measurements, Recurring | Municipal securities |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Total fixed maturity securities | 3,116,543 | 2,987,054
Fair Value, Measurements, Recurring | Municipal securities | Level 1 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Total fixed maturity securities | 0 | 0
Fair Value, Measurements, Recurring | Municipal securities | Level 2 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Total fixed maturity securities | 3,116,543 | 2,987,054
Fair Value, Measurements, Recurring | Municipal securities | Level 3 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Total fixed maturity securities | 0 | 0
Fair Value, Measurements, Recurring | Mortgage-backed securities |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Total fixed maturity securities | 293,169 | 259,421
Fair Value, Measurements, Recurring | Mortgage-backed securities | Level 1 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Total fixed maturity securities | 0 | 0
Fair Value, Measurements, Recurring | Mortgage-backed securities | Level 2 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Total fixed maturity securities | 293,169 | 259,421
Fair Value, Measurements, Recurring | Mortgage-backed securities | Level 3 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Total fixed maturity securities | 0 | 0
Fair Value, Measurements, Recurring | Corporate securities |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Total fixed maturity securities | 763,253 | 841,715
Fair Value, Measurements, Recurring | Corporate securities | Level 1 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Total fixed maturity securities | 0 | 0
Fair Value, Measurements, Recurring | Corporate securities | Level 2 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Total fixed maturity securities | 763,253 | 841,715
Fair Value, Measurements, Recurring | Corporate securities | Level 3 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Total fixed maturity securities | 0 | 0
Fair Value, Measurements, Recurring | Collateralized loan obligations |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Total fixed maturity securities | 650,081 | 626,255
Fair Value, Measurements, Recurring | Collateralized loan obligations | Level 1 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Total fixed maturity securities | 0 | 0
Fair Value, Measurements, Recurring | Collateralized loan obligations | Level 2 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Total fixed maturity securities | 650,081 | 626,255
Fair Value, Measurements, Recurring | Collateralized loan obligations | Level 3 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Total fixed maturity securities | 0 | 0
Fair Value, Measurements, Recurring | Other asset-backed securities |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Total fixed maturity securities | 107,103 | 105,096
Fair Value, Measurements, Recurring | Other asset-backed securities | Level 1 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Total fixed maturity securities | 0 | 0
Fair Value, Measurements, Recurring | Other asset-backed securities | Level 2 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Total fixed maturity securities | 107,103 | 105,096
Fair Value, Measurements, Recurring | Other asset-backed securities | Level 3 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Total fixed maturity securities | 0 | 0
Fair Value, Measurements, Recurring | Common stock |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Equity securities | 549,027 | 741,369
Fair Value, Measurements, Recurring | Common stock | Level 1 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Equity securities | 549,027 | 741,369
Fair Value, Measurements, Recurring | Common stock | Level 2 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Equity securities | 0 | 0
Fair Value, Measurements, Recurring | Common stock | Level 3 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Equity securities | 0 | 0
Fair Value, Measurements, Recurring | Non-redeemable preferred stock |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Equity securities | 41,458 | 42,603
Fair Value, Measurements, Recurring | Non-redeemable preferred stock | Level 1 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Equity securities | 0 | 0
Fair Value, Measurements, Recurring | Non-redeemable preferred stock | Level 2 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Equity securities | 41,458 | 42,603
Fair Value, Measurements, Recurring | Non-redeemable preferred stock | Level 3 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Equity securities | 0 | 0
Fair Value, Measurements, Recurring | Private equity funds measured at net asset value |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Equity securities | 97,167 | 95,203
Fair Value, Measurements, Recurring | Short-term bonds |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Short-term investments | 9,000 | 1,655
Fair Value, Measurements, Recurring | Short-term bonds | Level 1 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Short-term investments | 0 | 0
Fair Value, Measurements, Recurring | Short-term bonds | Level 2 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Short-term investments | 9,000 | 1,655
Fair Value, Measurements, Recurring | Short-term bonds | Level 3 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Short-term investments | 0 | 0
Fair Value, Measurements, Recurring | Money market instruments |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Short-term investments | 272,750 | 282,141
Fair Value, Measurements, Recurring | Money market instruments | Level 1 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Short-term investments | 272,750 | 282,141
Fair Value, Measurements, Recurring | Money market instruments | Level 2 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Short-term investments | 0 | 0
Fair Value, Measurements, Recurring | Money market instruments | Level 3 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Short-term investments | 0 | 0
Fair Value, Measurements, Recurring | Other |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Short-term investments | 16 | 21
Fair Value, Measurements, Recurring | Other | Level 1 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Short-term investments | 16 | 21
Fair Value, Measurements, Recurring | Other | Level 2 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Short-term investments | 0 | 0
Fair Value, Measurements, Recurring | Other | Level 3 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Short-term investments | 0 | 0
Fair Value, Measurements, Recurring | Options sold |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Options sold | 1,397 | 213
Fair Value, Measurements, Recurring | Options sold | Level 1 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Options sold | 1,397 | 213
Fair Value, Measurements, Recurring | Options sold | Level 2 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Options sold | 0 | 0
Fair Value, Measurements, Recurring | Options sold | Level 3 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Options sold | $ 0 | $ 0

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- Definition Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. 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