Derivative Financial Instruments - Schedule of Carrying Amount of Hedged Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Derivatives designated as hedging instruments | Long-term debt
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Carrying Amount of Assets	$ 15,951	$ 12,463
Active	(323)	(340)
Derivatives designated as hedging instruments | Total available-for-sale investment securities
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Carrying Amount of Assets	18,666	11,260
Active	(376)	(503)
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	3,320	685
Active	(26)	(6)
Last-of-layer, amount	1,820	400
Derivatives not designated as hedging instruments | Long-term debt
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Carrying Amount of Assets	103	156
Derivatives not designated as hedging instruments | Total available-for-sale investment securities
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Carrying Amount of Assets	$ 1	$ 3