Derivative Instruments - Gains (Losses) Recognized in Earnings for Other Economic Hedges and Customer-Related Positions (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Customer-Related Positions | Interest rate contracts | Purchased and written options
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recognized in earnings	$ (5)	$ 109	$ 9	$ 41
Customer-Related Positions | Interest rate contracts | Futures
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recognized in earnings	1	0	3	0
Customer-Related Positions | Swaps
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recognized in earnings	61	(55)	143	165
Customer-Related Positions | Credit contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recognized in earnings	(4)	(3)	(10)	(3)
Customer-Related Positions | Foreign exchange rate contracts | Purchased and written options
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recognized in earnings	0	0	1	0
Customer-Related Positions | Foreign exchange rate contracts | Forwards, spots and swaps
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recognized in earnings	69	70	183	126
Customer-Related Positions | Commodity contracts | Purchased and written options
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recognized in earnings	1	1	15	5
Customer-Related Positions | Commodity contracts | Futures
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recognized in earnings	35	4	39	10
Customer-Related Positions | Commodity contracts | Swaps
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recognized in earnings	(30)	(2)	(26)	(1)
Asset and Liability Management Positions | Other economic hedges | Interest rate contracts | Futures and forwards
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recognized in earnings	18	2	43	(12)
Asset and Liability Management Positions | Other economic hedges | Interest rate contracts | Purchased and written options
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recognized in earnings	43	64	111	112
Asset and Liability Management Positions | Other economic hedges | Swaps
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recognized in earnings	12	107	81	30
Asset and Liability Management Positions | Other economic hedges | Foreign exchange forward contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recognized in earnings	13	(6)	(4)	2
Asset and Liability Management Positions | Other economic hedges | Equity contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recognized in earnings	20	(2)	28	(4)
Asset and Liability Management Positions | Other economic hedges | Credit contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recognized in earnings	1	(5)	6	(7)
Asset and Liability Management Positions | Other economic hedges | Other
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recognized in earnings	$ (7)	$ (1)	$ (89)	$ (70)