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Claim and Claim Adjustment Expense Reserves (Narrative) (Details) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended |  |
--- | --- | --- | --- | ---
Jun. 30, 2023 | Jun. 30, 2022 | Jun. 30, 2023 | Jun. 30, 2022 | Dec. 31, 2022 | Dec. 31, 2010
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Unusual or Infrequent Item, or Both, Net of Insurance Proceeds | $ 68 | $ 37 | $ 120 | $ 57 |  |
Total pretax (favorable) unfavorable development | 18 | 27 | 31 | 15 |  |
Retroactive reinsurance benefit recognized | 15 | 11 | 23 | 23 |  |
Cumulative amounts ceded under AEP Loss Portfolio Transfer | 3,500 |  | 3,500 |  | $ 3,500 |
Corporate & Other |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Total pretax (favorable) unfavorable development | 35 | $ 64 | 35 | $ 64 |  |
Asbestos and Environmental Reserves |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net A&EP claim and allocated claim adjustment expense reserves ceded to NICO |  |  |  |  |  | $ 1,600
Aggregate limit under A&EP Loss Portfolio Transfer |  |  |  |  |  | 4,000
A&EP claim and allocated claim adjustment expense reserves ceded under existing third party reinsurance contracts transferred to NICO under A&EP Loss Portfolio Transfer |  |  |  |  |  | 1,200
Reinsurance premium paid to NICO under A&EP Loss Portfolio Transfer |  |  |  |  |  | 2,000
Net reinsurance receivables transferred to NICO under A&EP Loss Portfolio Transfer |  |  |  |  |  | 215
Total consideration paid to NICO under AEP Loss Portfolio Transfer |  |  |  |  |  | $ 2,200
Deferred reinsurance benefit yet to be recognized | 402 |  | 402 |  | $ 425 |
Fair value of collateral trust account established by NICO under A&EP Loss Portfolio Transfer | $ 2,400 |  | $ 2,400 |  |  |

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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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