Derivative Financial Instruments - Impact of Derivatives on Consolidated Statement of Income (Details) - Derivatives not designated as hedging instruments - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Derivative [Line Items]
Amount of gain (loss) on derivative recognized in income	$ 347	$ 293
Foreign exchange contracts | Foreign exchange trading services revenue
Derivative [Line Items]
Amount of gain (loss) on derivative recognized in income	323	233
Foreign exchange contracts | Interest expense
Derivative [Line Items]
Amount of gain (loss) on derivative recognized in income	29	83
Interest rate contracts
Derivative [Line Items]
Amount of gain (loss) on derivative recognized in income	1	6
Other derivative contracts | Other fee revenue
Derivative [Line Items]
Amount of gain (loss) on derivative recognized in income	8	6
Other derivative contracts | Compensation and employee benefits
Derivative [Line Items]
Amount of gain (loss) on derivative recognized in income	$ (14)	$ (35)