Fair Value of Financial Instruments - Changes in Unrealized Gains (Losses) Included in OCI (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Fair Value Assets and Liabilities Measured on Recurring Basis Level 3 Activity [Line Items]
Unrealized gains (losses) included in OCI, net	$ 32	$ 92	$ 31	$ 35
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)	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	$ 0	$ 39	$ (16)	$ 2
RMBS
Fair Value Assets and Liabilities Measured on Recurring Basis Level 3 Activity [Line Items]
Unrealized gains (losses) included in OCI, net	0	1	0	0
CMBS
Fair Value Assets and Liabilities Measured on Recurring Basis Level 3 Activity [Line Items]
Unrealized gains (losses) included in OCI, net	1	0	1	0
ABS
Fair Value Assets and Liabilities Measured on Recurring Basis Level 3 Activity [Line Items]
Unrealized gains (losses) included in OCI, net	32	47	43	26
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	0	1	0	2
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	$ (1)	$ 4	$ 3	$ 5