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Claim and Claim Adjustment Expense Reserves (Reconciliation of Liability for Unpaid Claim and Claim Adjustment Expense) (Details) - USD ($) $ in Millions | Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021
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Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |
Total Net Carried Claim and Claim Adjustment Expense Reserves | $ 19,263 | $ 18,163 | $ 16,929 | $ 16,300
Reinsurance receivables | 5,713 |  |  |
Total gross liability for unpaid claim and claim adjustment expenses | 24,976 | 23,304 | $ 22,120 |
Specialty |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |
Total Net Carried Claim and Claim Adjustment Expense Reserves | 5,979 | 5,916 |  |
Reinsurance receivables | 1,447 |  |  |
Commercial |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |
Total Net Carried Claim and Claim Adjustment Expense Reserves | 9,939 | 9,021 |  |
Reinsurance receivables | 1,397 |  |  |
International |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |
Total Net Carried Claim and Claim Adjustment Expense Reserves | 2,416 | 2,276 |  |
Reinsurance receivables | 504 |  |  |
Life and Group |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |
Total Net Carried Claim and Claim Adjustment Expense Reserves | 541 |  |  |
Reinsurance receivables | 81 |  |  |
Corporate & Other |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |
Total Net Carried Claim and Claim Adjustment Expense Reserves | 388 | $ 368 |  |
Reinsurance receivables | $ 2,284 |  |  |

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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://www.xbrl.org/2003/role/exampleRef -Topic 944 -SubTopic 40 -Name Accounting Standards Codification -Section 55 -Paragraph 7 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480046/944-40-55-7 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Topic 944 -SubTopic 40 -Name Accounting Standards Codification -Section 55 -Paragraph 9E -Publisher FASB -URI https://asc.fasb.org/1943274/2147480046/944-40-55-9E Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -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 4: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 944 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(13)(a)(1)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478777/944-210-S99-1 + Details
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- Definition Liability as of the balance sheet date for amounts representing estimated cost of settling unpaid claims under the terms of the underlying insurance policies, less estimated reinsurance recoveries on such claims. This includes an estimate for claims which have been incurred but not reported. Claim adjustment expenses represent the costs estimated to be incurred in the settlement of unpaid claims. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 944 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(13)(a)(1)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478777/944-210-S99-1 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -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 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 40 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480081/944-40-50-3 + Details
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