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	$ 19	$ 269	$ 87
Transfers Out of Level 3	(181)	(210)	(257)	(510)
Total	(181)	(191)	12	(423)
Corporate bonds
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net [Abstract]
Transfers Into Level 3	0	0	112	19
Transfers Out of Level 3	(42)	(7)	(43)	(143)
Total	(42)	(7)	69	(124)
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)
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	(68)	(5)	(75)	(5)
Total	(68)	(5)	(75)	(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)
ABS
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net [Abstract]
Transfers Into Level 3	0	0	70	49
Transfers Out of Level 3	(71)	(178)	(123)	(286)
Total	(71)	(178)	(53)	(237)
Hybrid and redeemable preferred securities
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net [Abstract]
Transfers Into Level 3	0	9	9	9
Transfers Out of Level 3	0	0	(9)	0
Total	0	9	0	9
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