Derivatives - Derivatives Associated with Fixed Income Trading Activities (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Customer interest rate contracts
Derivative Instruments, Gain (Loss) [Line Items]
Notional	$ 4,444	$ 4,096
Assets	26	8
Liabilities	108	190
Offsetting upstream interest rate contracts
Derivative Instruments, Gain (Loss) [Line Items]
Notional	4,603	4,265
Assets	73	134
Liabilities	25	9
Forwards and futures purchased
Derivative Instruments, Gain (Loss) [Line Items]
Notional	2,290	1,421
Assets	6	1
Liabilities	2	6
Forwards and futures sold
Derivative Instruments, Gain (Loss) [Line Items]
Notional	2,447	1,426
Assets	3	7
Liabilities	$ 5	$ 0