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Related Party Transactions (Narrative) (Details) - USD ($) $ in Thousands |  | 12 Months Ended
--- | --- | ---
Jun. 01, 2023 | Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021
Related Party Transaction [Line Items] |  |  |  |
Services and other revenues |  | $ 2,704,512 | $ 2,809,425 | $ 2,285,325
Reinsurance recoverables |  | 9,235,501 | 8,446,745 |
Gain on sale of business |  | 18,965 | 225,832 | 22,085
ISIC [Member] |  |  |  |
Related Party Transaction [Line Items] |  |  |  |
Gain on sale of business | $ 16,900 |  |  |
Nephila Reinsurers [Member] |  |  |  |
Related Party Transaction [Line Items] |  |  |  |
Reinsurance recoverables |  | 794,300 | 1,400,000 |
Hagerty [Member] |  |  |  |
Related Party Transaction [Line Items] |  |  |  |
Reinsurance recoverables |  | 214,800 | 159,700 |
Insurance-linked Securities Operations [Member] | Unconsolidated entities managed by Nephila [Member] |  |  |  |
Related Party Transaction [Line Items] |  |  |  |
Services and other revenues |  | $ 97,500 | $ 79,500 | $ 141,900

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- Definition Amount of gain (loss) from sale and disposal of integrated set of activities and assets capable of being conducted and managed for purpose of providing return in form of dividend, lower cost, or other economic benefit to investor, owner, member and participant. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 230 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 28 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org//1943274/2147482740/230-10-45-28 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 810 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 1B -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481203/810-10-50-1B + Details
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- Definition Amount, after valuation allowance, recoverable under reinsurance contracts. Examples include, but are not limited to, settled and unsettled claims, incurred but not reported losses, loss adjustment expense, policy benefits and policy reserves. Excludes premiums paid under reinsurance contracts. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 944 -SubTopic 310 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Publisher FASB -URI https://asc.fasb.org//1943274/2147479584/944-310-50-2 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 944 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Publisher FASB -URI https://asc.fasb.org//1943274/2147479838/944-20-50-5 Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 944 -SubTopic 310 -Name Accounting Standards Codification -Section 45 -Paragraph 5 -Publisher FASB -URI https://asc.fasb.org//1943274/2147479616/944-310-45-5 Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 944 -SubTopic 310 -Name Accounting Standards Codification -Section 45 -Paragraph 6 -Publisher FASB -URI https://asc.fasb.org//1943274/2147479616/944-310-45-6 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 825 -Name Accounting Standards Codification -Section 50 -Paragraph 1B -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147479383/944-825-50-1B + Details
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