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	$ 4	$ (1,713)	$ (171)
Corporate bonds
Fair Value Assets and Liabilities Measured on Recurring Basis Level 3 Activity [Line Items]
Unrealized gains (losses) included in OCI, net	(5)	(1,562)	(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	(116)	(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)	(22)	27
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