Derivative Financial Instruments - Notional and Fair Values (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Derivatives Instruments and Hedging Activities Disclosure [Line Items]
Derivatives, Asset Fair Value	$ 174	$ 239
Derivatives, Liability Fair Value	244	291
Not Designated as Hedging Instrument | Credit contracts
Derivatives Instruments and Hedging Activities Disclosure [Line Items]
Derivative, Notional Amount	61
Interest rate contracts
Derivatives Instruments and Hedging Activities Disclosure [Line Items]
Hedged Asset, Fair Value Hedge	202	202
Hedged Asset, Fair Value Hedge, Cumulative Increase (Decrease)	2	2
Interest rate contracts | Not Designated as Hedging Instrument
Derivatives Instruments and Hedging Activities Disclosure [Line Items]
Derivative, Notional Amount	12,596	11,626
Derivatives, Asset Fair Value	131	201
Derivatives, Liability Fair Value	221	266
Interest rate contracts | Fair Value Hedging [Member] | Designated as Hedging Instrument
Derivatives Instruments and Hedging Activities Disclosure [Line Items]
Derivative, Notional Amount	0	0
Derivatives, Asset Fair Value	0	0
Derivatives, Liability Fair Value	0	0
Interest rate contracts | Cash flow hedges | Designated as Hedging Instrument
Derivatives Instruments and Hedging Activities Disclosure [Line Items]
Derivative, Notional Amount	270	10
Derivatives, Asset Fair Value	1	0
Derivatives, Liability Fair Value	0	0
Foreign exchange contracts | Not Designated as Hedging Instrument
Derivatives Instruments and Hedging Activities Disclosure [Line Items]
Derivative, Notional Amount	94	44
Derivatives, Asset Fair Value	1	1
Derivatives, Liability Fair Value	1	0
Foreign exchange contracts | Cash flow hedges | Designated as Hedging Instrument
Derivatives Instruments and Hedging Activities Disclosure [Line Items]
Derivative, Notional Amount	433	504
Derivatives, Asset Fair Value	9	37
Derivatives, Liability Fair Value	16	2
Credit Risk Contract | Not Designated as Hedging Instrument
Derivatives Instruments and Hedging Activities Disclosure [Line Items]
Derivative, Notional Amount		72
Derivatives, Asset Fair Value	0	0
Derivatives, Liability Fair Value	0	0
Fixed maturities | Not Designated as Hedging Instrument
Derivatives Instruments and Hedging Activities Disclosure [Line Items]
Derivatives, Asset Fair Value	3	0
Derivatives, Liability Fair Value	0	4
Embedded derivatives within reinsurance | Not Designated as Hedging Instrument
Derivatives Instruments and Hedging Activities Disclosure [Line Items]
Derivatives, Asset Fair Value	29	0
Derivatives, Liability Fair Value	0	0
Managed Custody Guarantees | Not Designated as Hedging Instrument
Derivatives Instruments and Hedging Activities Disclosure [Line Items]
Derivatives, Asset Fair Value	0	0
Derivatives, Liability Fair Value	1	4
Stabilizer | Not Designated as Hedging Instrument
Derivatives Instruments and Hedging Activities Disclosure [Line Items]
Derivatives, Asset Fair Value	0	0
Derivatives, Liability Fair Value	$ 5	$ 15