Derivative and Hedging Activities - Net Gain (Loss) Recognized on Designated Instruments (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2023
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized in AOCL	$ (72)	$ (65)
Futures | Net return on mortgage servicing rights
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized in AOCL	0	3
Interest rate swaps and swaptions | Net return on mortgage servicing rights
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized in AOCL	(61)	(83)
Mortgage-backed securities forwards | Net return on mortgage servicing rights
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized in AOCL	(12)	(25)
Rate lock commitments and US Treasury futures | Net gain on loan sales
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized in AOCL	1	39
Interest rate swaps | Other noninterest income
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized in AOCL	$ 0	$ 1