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Reserve for Property and Casualty Insurance Claims and Claims Expense - Schedule of Prior Year Reserve Re-Estimates Included in Claims and Claims Expense (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2024 | Sep. 30, 2023 | Sep. 30, 2024 | Sep. 30, 2023
Increase (decrease) in claims and claims expense |  |  |  |
Prior years | $ 32 | $ 183 | $ (322) | $ 380
Auto |  |  |  |
Increase (decrease) in claims and claims expense |  |  |  |
Prior years | (65) | 33 | (319) | 105
Homeowners |  |  |  |
Increase (decrease) in claims and claims expense |  |  |  |
Prior years | (12) | 62 | (392) | 136
Other personal lines |  |  |  |
Increase (decrease) in claims and claims expense |  |  |  |
Prior years | 51 | (14) | 164 | (8)
Commercial lines |  |  |  |
Increase (decrease) in claims and claims expense |  |  |  |
Prior years | 1 | 19 | 159 | 51
Other business lines |  |  |  |
Increase (decrease) in claims and claims expense |  |  |  |
Prior years | (3) | 1 | 1 | 12
Run-off Property-Liability |  |  |  |
Increase (decrease) in claims and claims expense |  |  |  |
Prior years | 59 | 82 | 65 | 85
Protection Services |  |  |  |
Increase (decrease) in claims and claims expense |  |  |  |
Prior years | 1 | 0 | 0 | (1)
Catastrophe losses |  |  |  |
Increase (decrease) in claims and claims expense |  |  |  |
Prior years | (14) | 17 | (314) | 6
Catastrophe losses | Auto |  |  |  |
Increase (decrease) in claims and claims expense |  |  |  |
Prior years | (10) | 6 | (26) | (41)
Catastrophe losses | Homeowners |  |  |  |
Increase (decrease) in claims and claims expense |  |  |  |
Prior years | (1) | 16 | (278) | 61
Catastrophe losses | Other personal lines |  |  |  |
Increase (decrease) in claims and claims expense |  |  |  |
Prior years | (3) | (11) | (5) | (23)
Catastrophe losses | Commercial lines |  |  |  |
Increase (decrease) in claims and claims expense |  |  |  |
Prior years | 0 | 6 | (5) | 9
Catastrophe losses | Other business lines |  |  |  |
Increase (decrease) in claims and claims expense |  |  |  |
Prior years | 0 | 0 | 0 | 0
Catastrophe losses | Run-off Property-Liability |  |  |  |
Increase (decrease) in claims and claims expense |  |  |  |
Prior years | 0 | 0 | 0 | 0
Catastrophe losses | Protection Services |  |  |  |
Increase (decrease) in claims and claims expense |  |  |  |
Prior years | 0 | 0 | 0 | 0
Non-catastrophe losses |  |  |  |
Increase (decrease) in claims and claims expense |  |  |  |
Prior years | 46 | 166 | (8) | 374
Non-catastrophe losses | Auto |  |  |  |
Increase (decrease) in claims and claims expense |  |  |  |
Prior years | (55) | 27 | (293) | 146
Non-catastrophe losses | Homeowners |  |  |  |
Increase (decrease) in claims and claims expense |  |  |  |
Prior years | (11) | 46 | (114) | 75
Non-catastrophe losses | Other personal lines |  |  |  |
Increase (decrease) in claims and claims expense |  |  |  |
Prior years | 54 | (3) | 169 | 15
Non-catastrophe losses | Commercial lines |  |  |  |
Increase (decrease) in claims and claims expense |  |  |  |
Prior years | 1 | 13 | 164 | 42
Non-catastrophe losses | Other business lines |  |  |  |
Increase (decrease) in claims and claims expense |  |  |  |
Prior years | (3) | 1 | 1 | 12
Non-catastrophe losses | Run-off Property-Liability |  |  |  |
Increase (decrease) in claims and claims expense |  |  |  |
Prior years | 59 | 82 | 65 | 85
Non-catastrophe losses | Protection Services |  |  |  |
Increase (decrease) in claims and claims expense |  |  |  |
Prior years | $ 1 | $ 0 | $ 0 | $ (1)

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- Definition Amount, after effects of reinsurance, of expense (reversal of expense) for claims incurred in prior reporting periods and related claims settlement costs. + 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/disclosureRef -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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