Derivatives - Derivative Gains and Losses (Details) - Not Designated as Hedging Instrument, Economic Hedge - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2026	Sep. 30, 2025
Derivative Instruments, Gain (Loss) [Line Items]
Derivative gains (losses)	$ 2,265	$ (317)	$ 2,957	$ (1,050)
Interest-rate management derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Derivative gains (losses)	2,142	(157)	2,719	(885)
Swaps
Derivative Instruments, Gain (Loss) [Line Items]
Derivative gains (losses)	535	108	1,016	(307)
Written options \| Written
Derivative Instruments, Gain (Loss) [Line Items]
Derivative gains (losses)	(663)	127	(590)	347
Purchased options \| Purchased
Derivative Instruments, Gain (Loss) [Line Items]
Derivative gains (losses)	1,774	(372)	1,630	(729)
Futures
Derivative Instruments, Gain (Loss) [Line Items]
Derivative gains (losses)	496	(20)	663	(196)
Mortgage commitment derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Derivative gains (losses)	832	(239)	994	(422)
CRT-Related Derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Derivative gains (losses)	18	10	74	26
Other
Derivative Instruments, Gain (Loss) [Line Items]
Derivative gains (losses)	$ (727)	$ 69	$ (830)	$ 231