Derivative Financial Instruments - Impact on Derivatives and Hedged Items on Consolidated Statement of Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount of Gain (Loss) on Derivative Recognized in Consolidated Statement of Income	$ (195)	$ (17)	$ 38
Amount of Gain (Loss) on Hedged Item Recognized in Consolidated Statement of Income	194	17	(38)
Net unrealized losses on AFS investment securities designated in fair value hedges recognized in OCI	362	93
Total available-for-sale investment securities | Net interest income | Interest rate contracts
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount of Gain (Loss) on Derivative Recognized in Consolidated Statement of Income	(424)	(55)	(164)
Amount of Gain (Loss) on Hedged Item Recognized in Consolidated Statement of Income	423	55	164
Total available-for-sale investment securities | Other fee revenue | Interest rate contracts
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount of Gain (Loss) on Derivative Recognized in Consolidated Statement of Income	(18)	21	0
Amount of Gain (Loss) on Hedged Item Recognized in Consolidated Statement of Income	18	(21)	0
Long-term debt | Net interest income | Interest rate contracts
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount of Gain (Loss) on Derivative Recognized in Consolidated Statement of Income	247	17	202
Amount of Gain (Loss) on Hedged Item Recognized in Consolidated Statement of Income	$ (247)	$ (17)	$ (202)