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Fair Value Measurements (Schedule Of Assets And Liabilities Measured At Fair Value On A Recurring Basis Valuation Techniques) (Details) - USD ($) $ in Thousands | Dec. 31, 2022 | Dec. 31, 2021
--- | --- | ---
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities (amortized cost $4,226,790; $3,909,780) | $ 4,088,311 | $ 4,031,523
Equity securities | 699,552 | 970,939
Fair Value, Measurements, Recurring |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities (amortized cost $4,226,790; $3,909,780) | 4,088,311 | 4,031,523
Equity securities | 699,552 | 970,939
Short-term investments | 122,937 | 140,127
Total assets at fair value | 4,910,800 | 5,142,589
Liabilities fair value | 162 | 301
Fair Value, Measurements, Recurring | U.S. government bonds |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities (amortized cost $4,226,790; $3,909,780) | 158,607 | 13,085
Fair Value, Measurements, Recurring | Municipal securities |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities (amortized cost $4,226,790; $3,909,780) | 2,737,183 | 2,843,221
Fair Value, Measurements, Recurring | Mortgage-backed securities |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities (amortized cost $4,226,790; $3,909,780) | 166,260 | 137,002
Fair Value, Measurements, Recurring | Corporate securities |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities (amortized cost $4,226,790; $3,909,780) | 569,553 | 523,853
Fair Value, Measurements, Recurring | Collateralized loan obligations |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities (amortized cost $4,226,790; $3,909,780) | 320,252 | 314,153
Fair Value, Measurements, Recurring | Other asset-backed securities |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities (amortized cost $4,226,790; $3,909,780) | 136,456 | 200,209
Fair Value, Measurements, Recurring | Common stock |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Equity securities | 558,169 | 797,024
Fair Value, Measurements, Recurring | Preferred stock |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Equity securities | 51,236 | 65,501
Fair Value, Measurements, Recurring | Private Equity Funds Net Asset Value |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Equity securities | 90,147 | 108,414
Fair Value, Measurements, Recurring | Short-term bonds |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Short-term investments | 59,876 | 17,201
Fair Value, Measurements, Recurring | Money market instruments |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Short-term investments | 63,021 | 122,917
Fair Value, Measurements, Recurring | Other |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Short-term investments | 40 | 9
Fair Value, Measurements, Recurring | Options sold |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Derivative liabilitly | 162 | 301
Fair Value, Measurements, Recurring | Level 1 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities (amortized cost $4,226,790; $3,909,780) | 103,519 | 13,085
Equity securities | 558,169 | 797,024
Short-term investments | 114,699 | 124,379
Total assets at fair value | 776,387 | 934,488
Liabilities fair value | 162 | 301
Fair Value, Measurements, Recurring | Level 1 | U.S. government bonds |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities (amortized cost $4,226,790; $3,909,780) | 103,519 | 13,085
Fair Value, Measurements, Recurring | Level 1 | Municipal securities |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities (amortized cost $4,226,790; $3,909,780) | 0 | 0
Fair Value, Measurements, Recurring | Level 1 | Mortgage-backed securities |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities (amortized cost $4,226,790; $3,909,780) | 0 | 0
Fair Value, Measurements, Recurring | Level 1 | Corporate securities |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities (amortized cost $4,226,790; $3,909,780) | 0 | 0
Fair Value, Measurements, Recurring | Level 1 | Collateralized loan obligations |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities (amortized cost $4,226,790; $3,909,780) | 0 | 0
Fair Value, Measurements, Recurring | Level 1 | Other asset-backed securities |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities (amortized cost $4,226,790; $3,909,780) | 0 | 0
Fair Value, Measurements, Recurring | Level 1 | Common stock |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Equity securities | 558,169 | 797,024
Fair Value, Measurements, Recurring | Level 1 | Preferred stock |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Equity securities | 0 | 0
Fair Value, Measurements, Recurring | Level 1 | Short-term bonds |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Short-term investments | 51,638 | 1,453
Fair Value, Measurements, Recurring | Level 1 | Money market instruments |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Short-term investments | 63,021 | 122,917
Fair Value, Measurements, Recurring | Level 1 | Other |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Short-term investments | 40 | 9
Fair Value, Measurements, Recurring | Level 1 | Options sold |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Derivative liabilitly | 162 | 301
Fair Value, Measurements, Recurring | Level 2 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities (amortized cost $4,226,790; $3,909,780) | 3,984,792 | 4,018,438
Equity securities | 51,236 | 65,501
Short-term investments | 8,238 | 15,748
Total assets at fair value | 4,044,266 | 4,099,687
Liabilities fair value | 0 | 0
Fair Value, Measurements, Recurring | Level 2 | U.S. government bonds |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities (amortized cost $4,226,790; $3,909,780) | 55,088 | 0
Fair Value, Measurements, Recurring | Level 2 | Municipal securities |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities (amortized cost $4,226,790; $3,909,780) | 2,737,183 | 2,843,221
Fair Value, Measurements, Recurring | Level 2 | Mortgage-backed securities |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities (amortized cost $4,226,790; $3,909,780) | 166,260 | 137,002
Fair Value, Measurements, Recurring | Level 2 | Corporate securities |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities (amortized cost $4,226,790; $3,909,780) | 569,553 | 523,853
Fair Value, Measurements, Recurring | Level 2 | Collateralized loan obligations |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities (amortized cost $4,226,790; $3,909,780) | 320,252 | 314,153
Fair Value, Measurements, Recurring | Level 2 | Other asset-backed securities |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities (amortized cost $4,226,790; $3,909,780) | 136,456 | 200,209
Fair Value, Measurements, Recurring | Level 2 | Common stock |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Equity securities | 0 | 0
Fair Value, Measurements, Recurring | Level 2 | Preferred stock |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Equity securities | 51,236 | 65,501
Fair Value, Measurements, Recurring | Level 2 | Short-term bonds |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Short-term investments | 8,238 | 15,748
Fair Value, Measurements, Recurring | Level 2 | Money market instruments |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Short-term investments | 0 | 0
Fair Value, Measurements, Recurring | Level 2 | Other |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Short-term investments | 0 | 0
Fair Value, Measurements, Recurring | Level 2 | Options sold |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Derivative liabilitly | 0 | 0
Fair Value, Measurements, Recurring | Level 3 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities (amortized cost $4,226,790; $3,909,780) | 0 | 0
Equity securities | 0 | 0
Short-term investments | 0 | 0
Total assets at fair value | 0 | 0
Liabilities fair value | 0 | 0
Fair Value, Measurements, Recurring | Level 3 | U.S. government bonds |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities (amortized cost $4,226,790; $3,909,780) | 0 | 0
Fair Value, Measurements, Recurring | Level 3 | Municipal securities |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities (amortized cost $4,226,790; $3,909,780) | 0 | 0
Fair Value, Measurements, Recurring | Level 3 | Mortgage-backed securities |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities (amortized cost $4,226,790; $3,909,780) | 0 | 0
Fair Value, Measurements, Recurring | Level 3 | Corporate securities |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities (amortized cost $4,226,790; $3,909,780) | 0 | 0
Fair Value, Measurements, Recurring | Level 3 | Collateralized loan obligations |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities (amortized cost $4,226,790; $3,909,780) | 0 | 0
Fair Value, Measurements, Recurring | Level 3 | Other asset-backed securities |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities (amortized cost $4,226,790; $3,909,780) | 0 | 0
Fair Value, Measurements, Recurring | Level 3 | Common stock |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Equity securities | 0 | 0
Fair Value, Measurements, Recurring | Level 3 | Preferred stock |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Equity securities | 0 | 0
Fair Value, Measurements, Recurring | Level 3 | Short-term bonds |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Short-term investments | 0 | 0
Fair Value, Measurements, Recurring | Level 3 | Money market instruments |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Short-term investments | 0 | 0
Fair Value, Measurements, Recurring | Level 3 | Other |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Short-term investments | 0 | 0
Fair Value, Measurements, Recurring | Level 3 | Options sold |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Derivative liabilitly | $ 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. Includes liabilities not subject to a master netting arrangement and not elected to be offset. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (c) -URI https://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 10 -URI https://asc.fasb.org/extlink&oid=99393222&loc=SL20226008-175313 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -URI https://asc.fasb.org/extlink&oid=123594938&loc=d3e13433-108611 Reference 4: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 22 -URI https://asc.fasb.org/extlink&oid=99393222&loc=SL20226052-175313 + Details
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- Definition Fair value of financial obligations, including, but not limited to, debt instruments, derivative liabilities, federal funds purchased and sold under agreements to repurchase, securities loaned or sold under agreements to repurchase, financial instruments sold not yet purchased, guarantees, line of credit, loans and notes payable, servicing liability, and trading liabilities. + References No definition available. + Details
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