v3.25.2
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