Derivative Instruments - FV Gains and Losses (Details) - 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]
Total derivatives fair value gains (losses), net	$ 1,816	$ (175)	$ 2,256	$ (576)
Net contractual interest income (expense) on interest-rate swaps	7,559	7,184	22,250	21,340
Pay-fixed
Derivative Instruments, Gain (Loss) [Line Items]
Total derivatives fair value gains (losses), net	4,859	(43)	6,583	(1,253)
Receive-fixed
Derivative Instruments, Gain (Loss) [Line Items]
Total derivatives fair value gains (losses), net	(5,793)	362	(7,567)	1,979
Basis
Derivative Instruments, Gain (Loss) [Line Items]
Total derivatives fair value gains (losses), net	(30)	7	(24)	8
Foreign currency
Derivative Instruments, Gain (Loss) [Line Items]
Total derivatives fair value gains (losses), net	(3)	(9)	(10)	23
Pay-fixed
Derivative Instruments, Gain (Loss) [Line Items]
Total derivatives fair value gains (losses), net	65	(79)	49	(94)
Receive-fixed
Derivative Instruments, Gain (Loss) [Line Items]
Total derivatives fair value gains (losses), net	(43)	(26)	(48)	(35)
Futures
Derivative Instruments, Gain (Loss) [Line Items]
Total derivatives fair value gains (losses), net	553	(1)	784	0
Interest rate caps
Derivative Instruments, Gain (Loss) [Line Items]
Total derivatives fair value gains (losses), net	16	0	16	0
Risk management derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Total derivatives fair value gains (losses), net	(419)	117	(273)	133
Net contractual interest income (expense) on interest-rate swaps	(43)	(94)	(56)	(495)
Mortgage commitment derivatives fair value gains (losses), net
Derivative Instruments, Gain (Loss) [Line Items]
Total derivatives fair value gains (losses), net	2,283	(295)	2,600	(684)
Credit enhancement derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Total derivatives fair value gains (losses), net	(1)	3	(17)	(25)
Other derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Total derivatives fair value gains (losses), net	$ (47)	$ 0	$ (54)	$ 0