Fair Value of Financial Instruments - Components of the Transfers In and Out of Level 3 (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net [Abstract]
Transfers Into Level 3	$ 0	$ 20	$ 270	$ 92
Transfers Out of Level 3	(191)	(210)	(268)	(510)
Total	(191)	(190)	2	(418)
Corporate bonds
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net [Abstract]
Transfers Into Level 3	0	0	112	22
Transfers Out of Level 3	(52)	(7)	(53)	(143)
Total	(52)	(7)	59	(121)
RMBS
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net [Abstract]
Transfers Into Level 3	0	0	0	0
Transfers Out of Level 3	(67)	(5)	(74)	(5)
Total	(67)	(5)	(74)	(5)
CMBS
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net [Abstract]
Transfers Into Level 3	0	0	0	0
Transfers Out of Level 3	0	(16)	(7)	(16)
Total	0	(16)	(7)	(16)
State and municipal bonds
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net [Abstract]
Transfers Into Level 3			0	0
Transfers Out of Level 3			0	(5)
Total			0	(5)
ABS
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net [Abstract]
Transfers Into Level 3	0	0	70	50
Transfers Out of Level 3	(72)	(178)	(124)	(286)
Total	(72)	(178)	(54)	(236)
Hybrid and redeemable preferred securities
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net [Abstract]
Transfers Into Level 3	0	10	10	10
Transfers Out of Level 3	0	0	(10)	0
Total	0	10	0	10
Trading securities
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net [Abstract]
Transfers Into Level 3			24	0
Transfers Out of Level 3			0	0
Total			24	0
Equity securities
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net [Abstract]
Transfers Into Level 3	0	0	54	0
Transfers Out of Level 3	0	(4)	0	(4)
Total	0	(4)	54	(4)
Derivative investments
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net [Abstract]
Transfers Into Level 3			0	0
Transfers Out of Level 3			0	(51)
Total			0	(51)
Other investments – short-term investments
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net [Abstract]
Transfers Into Level 3	0	10	0	10
Transfers Out of Level 3	0	0	0	0
Total	$ 0	$ 10	$ 0	$ 10