Derivative Instruments - FV Gains and Losses (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Derivative Instruments, Gain (Loss) [Line Items]
Total risk management derivatives fair value gains (losses), net	$ 1,211	$ 514	$ 2,991
Net contractual interest expense on interest-rate swaps	$ 28,748	$ 28,773	$ 29,423
Derivative Gain Loss Statement Of Income Or Comprehensive Income Extensible Enumeration Not Disclosed Flag	Total derivatives fair value gains (losses), net	Total derivatives fair value gains (losses), net	Total derivatives fair value gains (losses), net
Pay-fixed
Derivative Instruments, Gain (Loss) [Line Items]
Total risk management derivatives fair value gains (losses), net	$ 1,472	$ (1,441)	$ 5,541
Receive-fixed
Derivative Instruments, Gain (Loss) [Line Items]
Total risk management derivatives fair value gains (losses), net	242	2,441	(4,788)
Basis
Derivative Instruments, Gain (Loss) [Line Items]
Total risk management derivatives fair value gains (losses), net	(22)	39	(143)
Foreign currency
Derivative Instruments, Gain (Loss) [Line Items]
Total risk management derivatives fair value gains (losses), net	(15)	32	(87)
Pay-fixed swaption
Derivative Instruments, Gain (Loss) [Line Items]
Total risk management derivatives fair value gains (losses), net	66	(2)	142
Receive-fixed swaption
Derivative Instruments, Gain (Loss) [Line Items]
Total risk management derivatives fair value gains (losses), net	(20)	(10)	(19)
Futures
Derivative Instruments, Gain (Loss) [Line Items]
Total risk management derivatives fair value gains (losses), net	1	0	(1)
Risk management derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Total risk management derivatives fair value gains (losses), net	760	348	380
Net contractual interest expense on interest-rate swaps	(964)	(711)	(265)
Mortgage commitment derivatives fair value gains (losses), net
Derivative Instruments, Gain (Loss) [Line Items]
Total risk management derivatives fair value gains (losses), net	533	120	2,708
Credit enhancement derivatives fair value gains (losses), net
Derivative Instruments, Gain (Loss) [Line Items]
Total risk management derivatives fair value gains (losses), net	$ (82)	$ 46	$ (97)