Fair Value of Financial Instruments - Changes in Unrealized Gains (Losses) Included in OCI (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Fair Value Assets and Liabilities Measured on Recurring Basis Level 3 Activity [Line Items]
Unrealized gains (losses) included in OCI, net	$ 16	$ (1,702)	$ (172)
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss), Statement of Other Comprehensive Income or Comprehensive Income [Extensible Enumeration]	Unrealized investment gain (loss)	Unrealized investment gain (loss)	Unrealized investment gain (loss)
Corporate bonds
Fair Value Assets and Liabilities Measured on Recurring Basis Level 3 Activity [Line Items]
Unrealized gains (losses) included in OCI, net	$ 7	$ (1,553)	$ (183)
State and municipal bonds
Fair Value Assets and Liabilities Measured on Recurring Basis Level 3 Activity [Line Items]
Unrealized gains (losses) included in OCI, net	3	(1)	0
Foreign government bonds
Fair Value Assets and Liabilities Measured on Recurring Basis Level 3 Activity [Line Items]
Unrealized gains (losses) included in OCI, net	0	(7)	(10)
ABS
Fair Value Assets and Liabilities Measured on Recurring Basis Level 3 Activity [Line Items]
Unrealized gains (losses) included in OCI, net	3	(115)	(9)
Hybrid and redeemable preferred securities
Fair Value Assets and Liabilities Measured on Recurring Basis Level 3 Activity [Line Items]
Unrealized gains (losses) included in OCI, net	(1)	(21)	26
Mortgage loans on real estate
Fair Value Assets and Liabilities Measured on Recurring Basis Level 3 Activity [Line Items]
Unrealized gains (losses) included in OCI, net	$ 4	$ (5)	$ 4

Fair Value Assets And Liabilities Measured On Recurring Basis Level 3 Activity [Line Items]

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- Definition

Amount of unrealized gain (loss) recognized in other comprehensive income (OCI) from asset measured at fair value on recurring basis using unobservable input (level 3) and still held.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482106/820-10-50-2

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- Definition

Indicates line item in statement in which other comprehensive income (OCI) is reported that includes unrealized gain (loss) from asset measured at fair value using unobservable input (level 3) and still held.

+ References

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