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Fair Value - Rollforward of Level 3 assets and liabilities (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2023 | Dec. 31, 2022
Other liabilities |  |  |
Level 3 liabilities rollforward |  |  |
Balance at beginning of year |  | $ (14) | $ (17)
Total gains or (losses) (realized/unrealized) - included in earnings | [1] | (1) | 0
Total gains or (losses) (realized/unrealized) - included in other comprehensive income |  | 0 | 1
Purchases, issuances, sales and settlements |  |  |
Purchases |  | 0 | 0
Issuances |  | (9) | 0
Sales |  | 0 | 0
Settlements |  | 2 | 2
Transfers in and/or out of Level 3 |  | 0 | 0
Balance at end of year |  | (22) | (14)
Equity securities |  |  |
Level 3 assets rollforward |  |  |
Balance at beginning of year |  | 4 | 3
Total gains or (losses) (realized/unrealized) - included in earnings | [1] | 0 | 0
Total gains or (losses) (realized/unrealized) - included in other comprehensive income |  | 0 | 0
Purchases, issuances, sales and settlements |  |  |
Purchases |  | 1 | 1
Issuances |  | 0 | 0
Sales |  | 0 | 0
Settlements |  | 0 | 0
Transfers in and/or out of Level 3 |  | 0 | 0
Balance at end of year |  | 5 | 4
Available for sale | Structured securities |  |  |
Level 3 assets rollforward |  |  |
Balance at beginning of year | [2] | 0 | 3
Total gains or (losses) (realized/unrealized) - included in earnings | [1],[2] | 0 | (1)
Total gains or (losses) (realized/unrealized) - included in other comprehensive income | [2] | 0 | 0
Purchases, issuances, sales and settlements |  |  |
Purchases | [2] | 0 | 0
Issuances | [2] | 0 | 0
Sales | [2] | 0 | (2)
Settlements | [2] | 0 | 0
Transfers in and/or out of Level 3 | [2] | 0 | 0
Balance at end of year | [2] | 0 | 0
Available for sale | Corporate bonds |  |  |
Level 3 assets rollforward |  |  |
Balance at beginning of year |  | 121 | 0
Total gains or (losses) (realized/unrealized) - included in earnings | [1] | 1 | 0
Total gains or (losses) (realized/unrealized) - included in other comprehensive income |  | (1) | (1)
Purchases, issuances, sales and settlements |  |  |
Purchases |  | 111 | 150
Issuances |  | 0 | 0
Sales |  | 0 | (6)
Settlements |  | (85) | (26)
Transfers in and/or out of Level 3 |  | 0 | 4
Balance at end of year |  | 147 | 121
Available for sale | Short-term investments |  |  |
Level 3 assets rollforward |  |  |
Balance at beginning of year |  | 0 | 0
Total gains or (losses) (realized/unrealized) - included in earnings | [1] | 0 | 0
Total gains or (losses) (realized/unrealized) - included in other comprehensive income |  | 0 | 0
Purchases, issuances, sales and settlements |  |  |
Purchases |  | 84 | 0
Issuances |  | 0 | 0
Sales |  | 0 | 0
Settlements |  | 0 | 0
Transfers in and/or out of Level 3 |  | 0 | 0
Balance at end of year |  | 84 | 0
Fair value option | Other investments |  |  |
Level 3 assets rollforward |  |  |
Balance at beginning of year |  | 33 | 28
Total gains or (losses) (realized/unrealized) - included in earnings | [1] | (5) | (1)
Total gains or (losses) (realized/unrealized) - included in other comprehensive income |  | 0 | 0
Purchases, issuances, sales and settlements |  |  |
Purchases |  | 107 | 12
Issuances |  | 0 | 0
Sales |  | (10) | (3)
Settlements |  | (19) | (3)
Transfers in and/or out of Level 3 |  | 0 | 0
Balance at end of year |  | 106 | 33
Fair value option | Short-term investments |  |  |
Level 3 assets rollforward |  |  |
Balance at beginning of year |  | 0 | 0
Total gains or (losses) (realized/unrealized) - included in earnings | [1] | 0 | 0
Total gains or (losses) (realized/unrealized) - included in other comprehensive income |  | 0 | 0
Purchases, issuances, sales and settlements |  |  |
Purchases |  | 11 | 0
Issuances |  | 0 | 0
Sales |  | 0 | 0
Settlements |  | (1) | 0
Transfers in and/or out of Level 3 |  | 0 | 0
Balance at end of year |  | 10 | 0
Fair value option | Equity securities |  |  |
Level 3 assets rollforward |  |  |
Balance at beginning of year |  | 4 | 5
Total gains or (losses) (realized/unrealized) - included in earnings | [1] | 0 | (1)
Total gains or (losses) (realized/unrealized) - included in other comprehensive income |  | 0 | 0
Purchases, issuances, sales and settlements |  |  |
Purchases |  | 0 | 0
Issuances |  | 0 | 0
Sales |  | 0 | 0
Settlements |  | 0 | 0
Transfers in and/or out of Level 3 |  | 0 | 0
Balance at end of year |  | $ 4 | $ 4
[1] | Gains or losses were included in net realized gains (losses).
[2] | Includes asset backed securities, mortgage backed securities and commercial mortgage backed securities

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