Derivatives - Derivative Gains and Losses (Details) - Not Designated as Hedging Instrument, Economic Hedge - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Derivative Instruments, Gain (Loss) [Line Items]
Derivative gains (losses)	$ (207)	$ 489	$ (733)	$ 1,107
Gain (Loss) on Derivative Instruments \| Interest-rate management derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Derivative gains (losses)	(155)	461	(728)	1,190
Gain (Loss) on Derivative Instruments \| Swaps
Derivative Instruments, Gain (Loss) [Line Items]
Derivative gains (losses)	(98)	136	(415)	398
Gain (Loss) on Derivative Instruments \| Written options \| Written
Derivative Instruments, Gain (Loss) [Line Items]
Derivative gains (losses)	94	(86)	220	(49)
Gain (Loss) on Derivative Instruments \| Purchased options \| Purchased
Derivative Instruments, Gain (Loss) [Line Items]
Derivative gains (losses)	(141)	242	(357)	298
Gain (Loss) on Derivative Instruments \| Futures
Derivative Instruments, Gain (Loss) [Line Items]
Derivative gains (losses)	(10)	169	(176)	543
Gain (Loss) on Derivative Instruments \| Mortgage commitment derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Derivative gains (losses)	(75)	32	(183)	72
Gain (Loss) on Derivative Instruments \| CRT-Related Derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Derivative gains (losses)	(28)	51	16	8
Gain (Loss) on Derivative Instruments \| Other
Derivative Instruments, Gain (Loss) [Line Items]
Derivative gains (losses)	$ 51	$ (55)	$ 162	$ (163)