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Fair Value of Assets and Liabilities - Schedule of Rollforward of Level 3 Assets and Liabilities Held at Fair Value (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2025 | Sep. 30, 2024 | Sep. 30, 2025 | Sep. 30, 2024
Assets |  |  |  |
Balance at beginning of period | $ 773 | $ 675 | $ 802 | $ 676
Total gains (losses) included in: Net income | 2 | 12 | 33 | 16
Total gains (losses) included in: OCI | 1 | 0 | 4 | 1
Transfers Into Level 3 | 1 | 0 | 27 | 0
Transfers Out of Level 3 | (63) | 0 | (96) | 0
Transfers (to) from held for sale |  | 0 |  | 0
Purchases | 59 | 39 | 102 | 94
Sales | (4) | (2) | (100) | (59)
Settlements | (3) | (1) | (6) | (5)
Balance at end of period | 766 | 723 | 766 | 723
Liabilities |  |  |  |
Balance at the beginning of the period | (1) | 0 | 0 | 0
Total gains (losses) included in: net income | 0 | 0 | (1) | 0
Total gains (losses) included in: OCI | 0 | 0 | 0 | 0
Transfers into Level 3 | 0 | 0 | 0 | 0
Transfers out of Level 3 | 0 | 0 | 0 | 0
Transfers (to) from held for sale |  | 0 |  | 0
Purchases | 0 | 0 | 0 | 0
Sales | 0 | 0 | 0 | 0
Settlements | 0 | 0 | 0 | 0
Balance at the end of the period | $ (1) | $ 0 | $ (1) | $ 0
Net investment income |  |  |  |
Total Level 3 gains (losses) included in net income |  |  |  |
Fair Value, Asset (Liability), Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration] | Net investment income | Net investment income | Net investment income | Net investment income
Gain (loss) included in earnings | $ 1 | $ 0 | $ 1 | $ 1
Net gains (losses) on investments and derivatives |  |  |  |
Total Level 3 gains (losses) included in net income |  |  |  |
Fair Value, Asset (Liability), Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration] | Net gains (losses) on investments and derivatives | Net gains (losses) on investments and derivatives | Net gains (losses) on investments and derivatives | Net gains (losses) on investments and derivatives
Gain (loss) included in earnings | $ (2) | $ 10 | $ 25 | $ 10
Operating costs and expenses |  |  |  |
Total Level 3 gains (losses) included in net income |  |  |  |
Fair Value, Asset (Liability), Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration] | Operating costs and expenses | Operating costs and expenses | Operating costs and expenses | Operating costs and expenses
Gain (loss) included in earnings | $ 3 | $ 2 | $ 6 | $ 5
Other liabilities |  |  |  |
Liabilities |  |  |  |
Balance at the beginning of the period | (1) |  | 0 |
Total gains (losses) included in: net income | 0 |  | (1) |
Total gains (losses) included in: OCI | 0 |  | 0 |
Transfers into Level 3 | 0 |  | 0 |
Transfers out of Level 3 | 0 |  | 0 |
Purchases | 0 |  | 0 |
Sales | 0 |  | 0 |
Settlements | 0 |  | 0 |
Balance at the end of the period | (1) |  | (1) |
Municipal |  |  |  |
Assets |  |  |  |
Balance at beginning of period | 2 | 7 | 2 | 11
Total gains (losses) included in: Net income | 0 | (2) | 0 | (2)
Total gains (losses) included in: OCI | 0 | 0 | 0 | 0
Transfers Into Level 3 | 1 | 0 | 1 | 0
Transfers Out of Level 3 | 0 | 0 | 0 | 0
Transfers (to) from held for sale |  | 0 |  | 0
Purchases | 0 | 0 | 0 | 0
Sales | 0 | 0 | 0 | (2)
Settlements | 0 | 0 | 0 | (2)
Balance at end of period | 3 | 5 | 3 | 5
Corporate - public |  |  |  |
Assets |  |  |  |
Balance at beginning of period | 35 | 30 | 22 | 26
Total gains (losses) included in: Net income | 0 | 0 | (1) | 1
Total gains (losses) included in: OCI | 0 | 0 | 1 | 1
Transfers Into Level 3 | 0 | 0 | 0 | 0
Transfers Out of Level 3 | 0 | 0 | (7) | 0
Transfers (to) from held for sale |  | (7) |  | (7)
Purchases | 0 | 5 | 20 | 16
Sales | (1) | 0 | (1) | (9)
Settlements | 0 | 0 | 0 | 0
Balance at end of period | 34 | 28 | 34 | 28
Corporate - privately placed |  |  |  |
Assets |  |  |  |
Balance at beginning of period | 109 | 50 | 110 | 58
Total gains (losses) included in: Net income | 0 | 0 | (1) | (6)
Total gains (losses) included in: OCI | 1 | 0 | 2 | 0
Transfers Into Level 3 | 0 | 0 | 0 | 0
Transfers Out of Level 3 | 0 | 0 | 0 | 0
Transfers (to) from held for sale |  | 0 |  | 0
Purchases | 48 | 1 | 48 | 1
Sales | 0 | 0 | 0 | (2)
Settlements | (2) | 0 | (3) | 0
Balance at end of period | 156 | 51 | 156 | 51
ABS |  |  |  |
Assets |  |  |  |
Balance at beginning of period | 39 |  | 26 |
Total gains (losses) included in: Net income | 0 |  | 0 |
Total gains (losses) included in: OCI | 0 |  | 0 |
Transfers Into Level 3 | 0 |  | 26 |
Transfers Out of Level 3 | (15) |  | (41) |
Purchases | 0 |  | 15 |
Sales | 0 |  | 0 |
Settlements | 0 |  | (2) |
Balance at end of period | 24 |  | 24 |
MBS |  |  |  |
Assets |  |  |  |
Balance at beginning of period | 88 |  | 88 |
Total gains (losses) included in: Net income | 0 |  | 0 |
Total gains (losses) included in: OCI | 0 |  | 0 |
Transfers Into Level 3 | 0 |  | 0 |
Transfers Out of Level 3 | 0 |  | 0 |
Purchases | 2 |  | 2 |
Sales | 0 |  | 0 |
Settlements | (1) |  | (1) |
Balance at end of period | 89 |  | 89 |
ABS and MBS |  |  |  |
Assets |  |  |  |
Balance at beginning of period |  | 71 |  | 58
Total gains (losses) included in: Net income |  | 0 |  | 0
Total gains (losses) included in: OCI |  | 0 |  | 0
Transfers Into Level 3 |  | 0 |  | 0
Transfers Out of Level 3 |  | 0 |  | 0
Transfers (to) from held for sale |  | 0 |  | 0
Purchases |  | 27 |  | 41
Sales |  | 0 |  | 0
Settlements |  | (1) |  | (2)
Balance at end of period |  | 97 |  | 97
Fixed income securities |  |  |  |
Assets |  |  |  |
Balance at beginning of period | 273 | 158 | 248 | 153
Total gains (losses) included in: Net income | 0 | (2) | (2) | (7)
Total gains (losses) included in: OCI | 1 | 0 | 3 | 1
Transfers Into Level 3 | 1 | 0 | 27 | 0
Transfers Out of Level 3 | (15) | 0 | (48) | 0
Transfers (to) from held for sale |  | (7) |  | (7)
Purchases | 50 | 33 | 85 | 58
Sales | (1) | 0 | (1) | (13)
Settlements | (3) | (1) | (6) | (4)
Balance at end of period | 306 | 181 | 306 | 181
Equity securities |  |  |  |
Assets |  |  |  |
Balance at beginning of period | 358 | 393 | 407 | 402
Total gains (losses) included in: Net income | (1) | 12 | 29 | 18
Total gains (losses) included in: OCI | 0 | 0 | 0 | 0
Transfers Into Level 3 | 0 | 0 | 0 | 0
Transfers Out of Level 3 | (48) | 0 | (48) | 0
Transfers (to) from held for sale |  | 0 |  | 0
Purchases | 3 | 5 | 8 | 14
Sales | (2) | (2) | (86) | (26)
Settlements | 0 | 0 | 0 | 0
Balance at end of period | 310 | 408 | 310 | 408
Short-term investments |  |  |  |
Assets |  |  |  |
Balance at beginning of period | 4 | 1 | 5 | 1
Total gains (losses) included in: Net income | 0 | 0 | 0 | 0
Total gains (losses) included in: OCI | 0 | 0 | 0 | 0
Transfers Into Level 3 | 0 | 0 | 0 | 0
Transfers Out of Level 3 | 0 | 0 | 0 | 0
Transfers (to) from held for sale |  | 0 |  | 0
Purchases | 6 | 1 | 9 | 22
Sales | (1) | 0 | (5) | (20)
Settlements | 0 | 0 | 0 | (1)
Balance at end of period | 9 | 2 | 9 | 2
Other investments |  |  |  |
Assets |  |  |  |
Balance at beginning of period | 1 | 2 | 1 | 2
Total gains (losses) included in: Net income | 0 | 0 | 0 | 0
Total gains (losses) included in: OCI | 0 | 0 | 0 | 0
Transfers Into Level 3 | 0 | 0 | 0 | 0
Transfers Out of Level 3 | 0 | 0 | 0 | 0
Transfers (to) from held for sale |  | 0 |  | 0
Purchases | 0 | 0 | 0 | 0
Sales | 0 | 0 | 0 | 0
Settlements | 0 | 0 | 0 | 0
Balance at end of period | 1 | 2 | 1 | 2
Other assets |  |  |  |
Assets |  |  |  |
Balance at beginning of period | 137 | 121 | 134 | 118
Total gains (losses) included in: Net income | 3 | 2 | 6 | 5
Total gains (losses) included in: OCI | 0 | 0 | 0 | 0
Transfers Into Level 3 | 0 | 0 | 0 | 0
Transfers Out of Level 3 | 0 | 0 | 0 | 0
Transfers (to) from held for sale |  | 0 |  | 0
Purchases | 0 | 0 | 0 | 0
Sales | 0 | 0 | 0 | 0
Settlements | 0 | 0 | 0 | 0
Balance at end of period | 140 | 123 | 140 | 123
Assets held for sale |  |  |  |
Assets |  |  |  |
Balance at beginning of period |  | 0 | 7 | 0
Total gains (losses) included in: Net income |  | 0 | 0 | 0
Total gains (losses) included in: OCI |  | 0 | 1 | 0
Transfers Into Level 3 |  | 0 | 0 | 0
Transfers Out of Level 3 |  | 0 | 0 | 0
Transfers (to) from held for sale |  | 7 |  | 7
Purchases |  | 0 | 0 | 0
Sales |  | 0 | (8) | 0
Settlements |  | 0 | 0 | 0
Balance at end of period | $ 0 | $ 7 | $ 0 | $ 7

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- Definition Amount of transfers of financial instrument classified as a liability out of level 3 of the fair value hierarchy. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2G -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2G Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-3 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (c)(3) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 + Details
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