Derivatives - Derivative Balance Sheet Classification (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	$ 5,769	$ 7,081
Fair Value	(2)	45
Asset Derivatives	60	88
Liability Derivatives	(62)	(43)
Available-for-sale Securities [Member]
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	588	647
Fair Value	0	0
Asset Derivatives	0	0
Liability Derivatives	0	0
Other investments
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	3,540	3,011
Fair Value	30	57
Asset Derivatives	30	66
Liability Derivatives	0	(9)
Other liabilities
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	1,641	3,423
Fair Value	(32)	(12)
Asset Derivatives	30	22
Liability Derivatives	(62)	(34)
Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	1,906	2,210
Fair Value	(2)	4
Asset Derivatives	29	36
Liability Derivatives	(31)	(32)
Interest rate swaps | Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	3,275	4,225
Fair Value	1	0
Asset Derivatives	1	0
Liability Derivatives	0	0
Interest rate swaps | Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	333	344
Foreign currency swaps | Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	588	646
Fair Value	(1)	41
Asset Derivatives	30	52
Liability Derivatives	(31)	(11)
Total cash flow hedges
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	3,863	4,871
Fair Value	0	41
Asset Derivatives	31	52
Liability Derivatives	(31)	(11)
Interest rate swaps and futures | Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	333	344
Fair Value	(2)	0
Asset Derivatives	0	1
Liability Derivatives	(2)	(1)
Foreign currency swaps | Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	588	647
Fair Value	0	0
Asset Derivatives	0	0
Liability Derivatives	0	0
Credit derivatives in offsetting positions | Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	985	986
Fair Value	0	0
Asset Derivatives	29	31
Liability Derivatives	(29)	(31)
Equity Option [Member] | Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	0	233
Fair Value	0	4
Asset Derivatives	0	4
Liability Derivatives	$ 0	$ 0