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Loss And Loss Adjustment Expense Reserves - Reconciliation of the Disclosure of Incurred and Paid Claims Development to the Loss and Loss Adjustment Expense Reserves (Details) - USD ($) $ in Thousands | Dec. 31, 2022 | Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019
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Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items] |  |  |  |
Net outstanding liabilities | $ 2,420,897 |  |  |
Reinsurance recoverables on unpaid losses | 25,323 |  |  |
Insurance lines other than short-duration | 1,077 |  |  |
Unallocated claims adjustment expenses | 137,613 |  |  |
Unallocated claims adjustment expenses, aggregate reconciling items | 138,690 |  |  |
Total gross loss and loss adjustment expense reserves | 2,584,910 | $ 2,226,430 | $ 1,991,304 | $ 1,921,255
Property insurance product line, automobile |  |  |  |
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items] |  |  |  |
Net outstanding liabilities | 1,905,140 |  |  |
Reinsurance recoverables on unpaid losses | 17,341 |  |  |
Property insurance product line, homeowners' |  |  |  |
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items] |  |  |  |
Net outstanding liabilities | 340,309 |  |  |
Reinsurance recoverables on unpaid losses | 6,952 |  |  |
Other Short-duration Insurance Product Line |  |  |  |
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items] |  |  |  |
Net outstanding liabilities | 175,448 |  |  |
Reinsurance recoverables on unpaid losses | $ 1,030 |  |  |

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- Definition The amount needed 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 -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 50 -Paragraph 3 -Subparagraph (a) -URI https://asc.fasb.org/extlink&oid=116884095&loc=d3e14764-158437 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 50 -Paragraph 3 -Subparagraph (cc) -URI https://asc.fasb.org/extlink&oid=116884095&loc=d3e14764-158437 + Details
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- Definition Amount, after valuation allowance, recoverable under reinsurance contracts for losses reported to the ceding insurer but not yet paid and amounts expected for incurred losses and settlement expenses, which have not yet been reported to the ceding insurer. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 310 -Section 45 -Paragraph 6 -URI https://asc.fasb.org/extlink&oid=99404803&loc=d3e21412-158489 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 20 -Section 50 -Paragraph 5 -URI https://asc.fasb.org/extlink&oid=99397103&loc=d3e6824-158387 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 50 -Paragraph 3 -Subparagraph (a) -URI https://asc.fasb.org/extlink&oid=116884095&loc=d3e14764-158437 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 50 -Paragraph 3 -Subparagraph (cc) -URI https://asc.fasb.org/extlink&oid=116884095&loc=d3e14764-158437 + Details
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- Definition Undiscounted amount, after reinsurance, of the liability for unpaid claims and allocated claim adjustment expense for short-duration insurance contracts. Excludes unallocated claim adjustment expense. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 50 -Paragraph 4C -URI https://asc.fasb.org/extlink&oid=116884468&loc=SL65671315-158438 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 50 -Paragraph 4B -URI https://asc.fasb.org/extlink&oid=116884468&loc=SL65671311-158438 + Details
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