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v3.23.2

Investments (Narrative) (Detail) $ in Millions | 3 Months Ended | 6 Months Ended | 12 Months Ended
--- | --- | --- | ---
Jun. 30, 2022 USD ($) | Jun. 30, 2023 USD ($) security | Jun. 30, 2022 USD ($) | Dec. 31, 2022 USD ($) security
Schedule Of Investments [Line Items] |  |  |  |
Fair value of securities on deposit with various regulatory authorities |  | $ 10 |  | $ 10
Number of securities in unrealized loss position for a continuous 12 month period | security |  | 597 |  | 210
Rate that a security's fair value is below book value |  | 5.00% |  | 5.00%
Increase decrease in other net realized (gains) losses |  | $ 17 | $ 19 |
Asset Pledged as Collateral [Member] |  |  |  |
Schedule Of Investments [Line Items] |  |  |  |
Fair value of securities pledged as collateral |  | $ 233 |  | $ 251
Securities In Unrealized Loss Position [Member] |  |  |  |
Schedule Of Investments [Line Items] |  |  |  |
Weighted average contractual maturity period in years for securities in an unrealized loss position |  | 14 years |  | 14 years
Increase decrease in other net realized (gains) losses | $ 19 |  | $ 19 |
Fair Value Below Book Value Greater Than Five Percent [Member] |  |  |  |
Schedule Of Investments [Line Items] |  |  |  |
Number of securities in unrealized loss position for a continuous 12 month period | security |  | 546 |  | 190

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