Derivative Financial Instruments - Schedule of Carrying Amount of Hedged Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Derivatives designated as hedging instruments | Long-term debt
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Carrying Amount of Assets	$ 15,553	$ 15,951
Active	(76)	(323)
Derivatives designated as hedging instruments | Total available-for-sale investment securities
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Carrying Amount of Assets	22,804	18,666
Active	99	(376)
Derivatives designated as hedging instruments | Total available-for-sale investment securities | Closed Portfolio
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Carrying Amount of Assets	3,300	3,320
Active	21	(26)
Last-of-layer, amount	1,730	1,820
Derivatives not designated as hedging instruments | Long-term debt
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Carrying Amount of Assets	72	103
Derivatives not designated as hedging instruments | Total available-for-sale investment securities
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Carrying Amount of Assets	$ 0	$ 1