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Reinsurance (Narrative) (Details) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021
Reinsurance Disclosures [Line Items] |  |  |
Percentage of ceded earned premiums to gross earned premiums | 39.00% | 38.00% | 38.00%
Percentage of assumed earned premiums to net earned premiums | 31.00% | 30.00% | 27.00%
Underwriting [Member] |  |  |
Reinsurance Disclosures [Line Items] |  |  |
Reinsurance recoverables | $ (1,496,265) | $ (834,648) | $ (893,230)
Reinsurance Recoverables, Gross | $ 4,000,000 | $ 3,100,000 |
Underwriting [Member] | Ten Largest Reinsurers [Member] |  |  |
Reinsurance Disclosures [Line Items] |  |  |
Recoverable balances as a percentage of the total balance | 65.00% | 62.00% |
Underwriting [Member] | RenaissanceRe |  |  |
Reinsurance Disclosures [Line Items] |  |  |
Recoverable balances as a percentage of the total balance | 17.00% |  |
Program services and other fronting [Member] |  |  |
Reinsurance Disclosures [Line Items] |  |  |
Reinsurance recoverables | $ 2,500,000 | $ 3,000,000 |
Program Services [Member] |  |  |
Reinsurance Disclosures [Line Items] |  |  |
Reinsurance Recoverables, Gross | $ 4,900,000 | $ 4,900,000 |
Program Services [Member] | Ten Largest Reinsurers [Member] |  |  |
Reinsurance Disclosures [Line Items] |  |  |
Recoverable balances as a percentage of the total balance | 56.00% | 67.00% |
Program Services [Member] | Knight Insurance Company |  |  |
Reinsurance Disclosures [Line Items] |  |  |
Recoverable balances as a percentage of the total balance | 10.00% |  |
Other fronting | Nephila Reinsurers [Member] |  |  |
Reinsurance Disclosures [Line Items] |  |  |
Recoverable balances as a percentage of the total balance | 100.00% |  |

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- References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 235 -Name Accounting Standards Codification -Section S99 -Paragraph 2 -Subparagraph (SX 210.12-17(Column A)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480149/944-235-S99-2 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 235 -Name Accounting Standards Codification -Section S99 -Paragraph 2 -Subparagraph (SX 210.12-17(Column B)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480149/944-235-S99-2 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 235 -Name Accounting Standards Codification -Section S99 -Paragraph 2 -Subparagraph (SX 210.12-17(Column C)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480149/944-235-S99-2 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 235 -Name Accounting Standards Codification -Section S99 -Paragraph 2 -Subparagraph (SX 210.12-17(Column D)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480149/944-235-S99-2 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 235 -Name Accounting Standards Codification -Section S99 -Paragraph 2 -Subparagraph (SX 210.12-17(Column E)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480149/944-235-S99-2 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 235 -Name Accounting Standards Codification -Section S99 -Paragraph 2 -Subparagraph (SX 210.12-17(Column F)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480149/944-235-S99-2 + Details
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- Definition Amount before 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, premium paid, policy benefits and policy reserves. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -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 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(6)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147479440/944-210-S99-1 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -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/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 14 -Publisher FASB -URI https://asc.fasb.org//1943274/2147479319/326-20-50-14 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Name Accounting Standards Codification -Section 50 -Paragraph 7A -SubTopic 10 -Topic 310 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481962/310-10-50-7A + Details
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