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Future Policy Benefit Reserves - Narrative (Details) - USD ($) $ in Millions | 3 Months Ended | 12 Months Ended
--- | --- | ---
Sep. 30, 2024 | Sep. 30, 2023 | Dec. 31, 2024 | Dec. 31, 2023
Insurance [Abstract] |  |  |  |
Liability for unpaid claims and claims adjustment expense, long term care policies, period increase (decrease) | $ 15 | $ 8 |  |
Liability for future policy benefit, expected future gross premium, discounted, before reinsurance |  |  | $ 3,573 | $ 3,824
Liability for future policy benefit, weighted-average duration |  |  | 11 years | 11 years
Liability future policy benefit, losses recognized in current period |  |  | $ 159 | $ 164
Liability future policy benefit, losses recognized in prior period |  |  | $ 29 | $ 42

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- Definition Liability For Future Policy Benefit, Losses Recognized In Current Period Reversed Due To Favorable Development + References No definition available. + Details
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- Definition Liability For Future Policy Benefit, Losses Recognized In Prior Period Reversed Due To Favorable Development + References No definition available. + Details
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- Definition Liability for Unpaid Claims and Claims Adjustment Expense, Long Term Care Policies, Period Increase (Decrease) + References No definition available. + Details
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- References No definition available. + Details
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- Definition Amount, before effect of reinsurance, of discounted balance for expected future gross premium component of liability for future policy benefit. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 40 -Name Accounting Standards Codification -Section 50 -Paragraph 6 -Subparagraph (b)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480081/944-40-50-6 + Details
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- Definition Weighted-average duration of liability for future policy benefit, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 40 -Name Accounting Standards Codification -Section 50 -Paragraph 6 -Subparagraph (b)(5) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480081/944-40-50-6 + Details
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