Derivative Financial Instruments - Impact of Derivatives on Consolidated Statement of Income (Details) - Derivatives not designated as hedging instruments - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Derivative [Line Items]
Amount of gain (loss) on derivative recognized in income	$ 301	$ 250	$ 594	$ 462
Foreign exchange contracts \| Foreign exchange trading services revenue
Derivative [Line Items]
Amount of gain (loss) on derivative recognized in income	279	208	512	415
Foreign exchange contracts \| Interest expense
Derivative [Line Items]
Amount of gain (loss) on derivative recognized in income	42	64	125	113
Interest rate contracts
Derivative [Line Items]
Amount of gain (loss) on derivative recognized in income	6	2	12	9
Other derivative contracts \| Other fee revenue
Derivative [Line Items]
Amount of gain (loss) on derivative recognized in income	(10)	(1)	(4)	(3)
Other derivative contracts \| Compensation and employee benefits
Derivative [Line Items]
Amount of gain (loss) on derivative recognized in income	$ (16)	$ (23)	$ (51)	$ (72)