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Reserve for Loss and Loss Expense (Roll Forward of Gross and Net Asbestos and Net Environmental Incurred Losses and Loss Expenses and Related Reserves) (Details) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |
Reserve for loss and loss expense at beginning of year, gross | $ 27,768 | $ 27,773 | $ 28,530
Incurred loss and loss expense, gross | 1,064 | 704 | 562
Less: loss and loss expense paid, Gross | (2,423) | (709) | (195)
Reserve for loss and loss expense at the end of year, gross | 26,409 | 27,768 | 27,773
Reserve for loss and loss expense at beginning of year, net | 20,329 | 21,075 | 21,421
Incurred loss and loss expense, Net | 748 | (205) | 37
Less: loss and loss expense paid, Net | (1,934) | (541) | (383)
Reserve for loss and loss expense at the end of year, net | 19,143 | 20,329 | 21,075
Asbestos [Member] |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |
Reserve for loss and loss expense at beginning of year, gross | 5,891 | 6,115 | 6,254
Incurred loss and loss expense, gross | 603 | 8 | 51
Less: loss and loss expense paid, Gross | (1,638) | (232) | (190)
Reserve for loss and loss expense at the end of year, gross | 4,856 | 5,891 | 6,115
Reserve for loss and loss expense at beginning of year, net | 4,660 | 4,884 | 5,023
Incurred loss and loss expense, Net | 515 | 8 | 51
Less: loss and loss expense paid, Net | (1,638) | (232) | (190)
Reserve for loss and loss expense at the end of year, net | 3,537 | 4,660 | 4,884
Enviromental [Member] |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |
Reserve for loss and loss expense at beginning of year, gross | 21,877 | 21,658 | 22,276
Incurred loss and loss expense, gross | 461 | 696 | 613
Less: loss and loss expense paid, Gross | (785) | (477) | (5)
Reserve for loss and loss expense at the end of year, gross | 21,553 | 21,877 | 21,658
Reserve for loss and loss expense at beginning of year, net | 15,669 | 16,191 | 16,398
Incurred loss and loss expense, Net | 233 | 213 | 14
Less: loss and loss expense paid, Net | (296) | (309) | (193)
Reserve for loss and loss expense at the end of year, net | $ 15,606 | $ 15,669 | $ 16,191

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- Definition Carrying amount as of the balance sheet date of reserves for the costs of settling insured claims and costs incurred in the claims settlement process attributable to asbestos and environmental claims, before estimated recoveries from reinsurers. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 944 -SubTopic 40 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (cc) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480081/944-40-50-3 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 50 -Paragraph 3 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480081/944-40-50-3 + Details
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- Definition Amount, before effects of reinsurance, of expense for claims incurred and costs incurred in the claim settlement process attributable to asbestos and environmental claims. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -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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- Definition Amount of cash outflow to settle insured claims and pay costs incurred in the claims settlement process attributable to asbestos and environmental claims. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 230 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 17 -Subparagraph (f) -Publisher FASB -URI https://asc.fasb.org//1943274/2147482740/230-10-45-17 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 944 -SubTopic 40 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480081/944-40-50-3 + Details
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- Definition Carrying amount as of the balance sheet date of reserves for the costs of settling insured claims and costs incurred in the claims settlement process attributable to asbestos and environmental claims, net of estimated reinsurance recoveries. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 944 -SubTopic 40 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (cc) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480081/944-40-50-3 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 50 -Paragraph 3 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480081/944-40-50-3 + Details
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