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Reserve for Loss and Loss Expense (Reserve Loss Development narrative) (Details) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021
Increase of net loss and loss expense reserves | $ 331,000 | $ 385,000 | $ 296,200
Anticipated recoveries for salvage and subrogation claims | 116,000 | 91,300 | 87,000
Prior year development | (9,954) | (78,890) | (82,853)
Favorable or unfavorable loss development [Member] |  |  |
Prior year development | $ (10,000) | $ (78,900) | $ (82,900)

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- Definition Amount of increase (decrease) in liability to reflect the estimated ultimate cost of settling claims relating to insured events that have occurred on or before the balance sheet date, whether or not reported to the insurer at that date. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 45 -Paragraph 28 -Subparagraph (a) -SubTopic 10 -Topic 230 -Publisher FASB -URI https://asc.fasb.org//1943274/2147482740/230-10-45-28 + Details
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- Definition The estimated amount as of the balance sheet date to be received by an insurer from the sale of property (usually damaged) on which the insurer has paid a total claim to the insured and has obtained title to the property and the right of an insurer to pursue any course of recovery of damages, in its name or in the name of the policyholder, against a third party who is liable for costs relating to an insured event that have been paid by the insurer. Estimated salvage and subrogation is generally deducted from the liability for unpaid claims. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 30 -Paragraph 2 -Publisher FASB -URI https://asc.fasb.org//1943274/2147479224/944-40-30-2 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 30 -Paragraph 3 -Publisher FASB -URI https://asc.fasb.org//1943274/2147479224/944-40-30-3 + Details
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- Definition Amount, after effects of reinsurance, of expense (reversal of expense) for claims incurred in prior reporting periods and related claims settlement costs. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 40 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480081/944-40-50-3 + Details
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- Details
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