Derivative Financial Instruments - Net Gains (Losses) Recorded in the Consolidated Statements of Income Relating to Free-Standing Derivative Instruments Used For Customer Accommodation (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Interest rate contracts | Contract revenue | Capital market fees
Derivative Instruments, Gain (Loss)
Net gains (losses) recorded in earnings	$ 9	$ 9	$ 24	$ 20
Interest rate contracts | Credit portion of fair value adjustment | Other noninterest expense
Derivative Instruments, Gain (Loss)
Net gains (losses) recorded in earnings	(1)	(4)	(5)	0
Interest rate contracts | Interest rate lock commitments | Mortgage banking net revenue
Derivative Instruments, Gain (Loss)
Net gains (losses) recorded in earnings	19	17	45	37
Commodity contracts | Contract revenue | Capital market fees
Derivative Instruments, Gain (Loss)
Net gains (losses) recorded in earnings	3	3	13	11
Commodity contracts | Credit portion of fair value adjustment | Other noninterest expense
Derivative Instruments, Gain (Loss)
Net gains (losses) recorded in earnings	0	0	0	1
Foreign exchange contracts | Other noninterest income
Derivative Instruments, Gain (Loss)
Net gains (losses) recorded in earnings	3	(1)	(2)	5
Foreign exchange contracts | Contract revenue | Capital market fees
Derivative Instruments, Gain (Loss)
Net gains (losses) recorded in earnings	17	18	55	57
Foreign exchange contracts | Contract revenue | Other noninterest income
Derivative Instruments, Gain (Loss)
Net gains (losses) recorded in earnings	$ 4	$ (16)	$ (29)	$ (13)