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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, 2022 | Dec. 31, 2021
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Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities: | $ 3,878,684 | $ 4,031,523
Equity securities: | 782,802 | 970,939
Fair Value, Measurements, Recurring |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities: | 3,878,684 | 4,031,523
Equity securities: | 782,802 | 970,939
Short-term investments: | 172,130 | 140,127
Assets, fair value disclosure | 4,833,616 | 5,142,589
Liabilities | 122 | 301
Fair Value, Measurements, Recurring | Level 1 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities: | 14,026 | 13,085
Equity securities: | 635,185 | 797,024
Short-term investments: | 157,466 | 124,379
Assets, fair value disclosure | 806,677 | 934,488
Liabilities | 122 | 301
Fair Value, Measurements, Recurring | Level 2 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities: | 3,864,658 | 4,018,438
Equity securities: | 57,721 | 65,501
Short-term investments: | 14,664 | 15,748
Assets, fair value disclosure | 3,937,043 | 4,099,687
Liabilities | 0 | 0
Fair Value, Measurements, Recurring | Level 3 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities: | 0 | 0
Equity securities: | 0 | 0
Short-term investments: | 0 | 0
Assets, fair value disclosure | 0 | 0
Liabilities | 0 | 0
Fair Value, Measurements, Recurring | U.S. government bonds |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities: | 14,026 | 13,085
Fair Value, Measurements, Recurring | U.S. government bonds | Level 1 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities: | 14,026 | 13,085
Fair Value, Measurements, Recurring | U.S. government bonds | Level 2 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities: | 0 | 0
Fair Value, Measurements, Recurring | U.S. government bonds | Level 3 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities: | 0 | 0
Fair Value, Measurements, Recurring | Municipal securities |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities: | 2,710,968 | 2,843,221
Fair Value, Measurements, Recurring | Municipal securities | Level 1 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities: | 0 | 0
Fair Value, Measurements, Recurring | Municipal securities | Level 2 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities: | 2,710,968 | 2,843,221
Fair Value, Measurements, Recurring | Municipal securities | Level 3 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities: | 0 | 0
Fair Value, Measurements, Recurring | Mortgage-backed securities |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities: | 156,074 | 137,002
Fair Value, Measurements, Recurring | Mortgage-backed securities | Level 1 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities: | 0 | 0
Fair Value, Measurements, Recurring | Mortgage-backed securities | Level 2 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities: | 156,074 | 137,002
Fair Value, Measurements, Recurring | Mortgage-backed securities | Level 3 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities: | 0 | 0
Fair Value, Measurements, Recurring | Corporate securities |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities: | 522,529 | 523,853
Fair Value, Measurements, Recurring | Corporate securities | Level 1 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities: | 0 | 0
Fair Value, Measurements, Recurring | Corporate securities | Level 2 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities: | 522,529 | 523,853
Fair Value, Measurements, Recurring | Corporate securities | Level 3 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities: | 0 | 0
Fair Value, Measurements, Recurring | Collateralized loan obligations |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities: | 301,046 | 314,153
Fair Value, Measurements, Recurring | Collateralized loan obligations | Level 1 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities: | 0 | 0
Fair Value, Measurements, Recurring | Collateralized loan obligations | Level 2 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities: | 301,046 | 314,153
Fair Value, Measurements, Recurring | Collateralized loan obligations | Level 3 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities: | 0 | 0
Fair Value, Measurements, Recurring | Other asset-backed securities |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities: | 174,041 | 200,209
Fair Value, Measurements, Recurring | Other asset-backed securities | Level 1 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
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] |  |
Fixed maturity securities: | 174,041 | 200,209
Fair Value, Measurements, Recurring | Other asset-backed securities | Level 3 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed maturity securities: | 0 | 0
Fair Value, Measurements, Recurring | Common stock |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Equity securities: | 635,185 | 797,024
Fair Value, Measurements, Recurring | Common stock | Level 1 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Equity securities: | 635,185 | 797,024
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: | 57,721 | 65,501
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: | 57,721 | 65,501
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: | 89,896 | 108,414
Fair Value, Measurements, Recurring | Short-term bonds |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Short-term investments: | 11,979 | 17,201
Fair Value, Measurements, Recurring | Short-term bonds | Level 1 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Short-term investments: | 795 | 1,453
Fair Value, Measurements, Recurring | Short-term bonds | Level 2 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Short-term investments: | 11,184 | 15,748
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: | 160,123 | 122,917
Fair Value, Measurements, Recurring | Money market instruments | Level 1 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Short-term investments: | 156,643 | 122,917
Fair Value, Measurements, Recurring | Money market instruments | Level 2 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Short-term investments: | 3,480 | 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: | 28 | 9
Fair Value, Measurements, Recurring | Other | Level 1 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Short-term investments: | 28 | 9
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] |  |
Derivative liability | 122 | 301
Fair Value, Measurements, Recurring | Options sold | Level 1 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Derivative liability | 122 | 301
Fair Value, Measurements, Recurring | Options sold | Level 2 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Derivative liability | 0 | 0
Fair Value, Measurements, Recurring | Options sold | Level 3 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Derivative liability | $ 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 Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI), classified as current. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(2)) -URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section 45 -Paragraph 1 -Subparagraph (f) -URI https://asc.fasb.org/extlink&oid=124098289&loc=d3e6676-107765 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 45 -Paragraph 1A -URI https://asc.fasb.org/extlink&oid=123594786&loc=SL75136599-209740 + 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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