Derivative Instruments - FV Gains and Losses (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Derivative Instruments, Gain (Loss) [Line Items]
Total derivatives fair value gains (losses), net	$ (338)	$ 1,353
Net contractual interest expense on interest-rate swaps	6,786	7,399
Interest income on mortgage loans	32,137	27,142
Long-term debt	(26,665)	(19,940)
Hedged asset, carrying amount	330,541		$ 293,788
Hedged asset, total basis adjustments	(440)		(628)
Hedged asset, discontinued fair value, remaining adjustments	(440)		(628)
Closed portfolio, amortized cost	132,035		98,377
Closed portfolio, designated UPB	3,787		5,187
Hedged liability, carrying amount	(74,239)		(73,790)
Hedged liability, total basis adjustments	4,278		4,713
Hedged liability, discontinued fair value, remaining adjustments	4,278		$ 4,713
Pay-fixed
Derivative Instruments, Gain (Loss) [Line Items]
Total derivatives fair value gains (losses), net	(1,590)	2,125
Receive-fixed
Derivative Instruments, Gain (Loss) [Line Items]
Total derivatives fair value gains (losses), net	1,572	(2,260)
Basis
Derivative Instruments, Gain (Loss) [Line Items]
Total derivatives fair value gains (losses), net	13	(68)
Foreign currency
Derivative Instruments, Gain (Loss) [Line Items]
Total derivatives fair value gains (losses), net	8	(24)
Pay-fixed
Derivative Instruments, Gain (Loss) [Line Items]
Total derivatives fair value gains (losses), net	(33)	44
Receive-fixed
Derivative Instruments, Gain (Loss) [Line Items]
Total derivatives fair value gains (losses), net	(1)	(3)
Futures
Derivative Instruments, Gain (Loss) [Line Items]
Total derivatives fair value gains (losses), net	0	0
Risk Management Derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Total derivatives fair value gains (losses), net	(209)	(197)
Net contractual interest expense on interest-rate swaps	(178)	(11)
Mortgage commitment derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Total derivatives fair value gains (losses), net	(114)	1,572
Credit enhancement derivatives fair value losses, net
Derivative Instruments, Gain (Loss) [Line Items]
Total derivatives fair value gains (losses), net	(15)	(22)
Interest rate risk on held-for-investment mortgage loan | Interest Income
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) in hedged item	177	(238)
Discontinued hedge related basis adjustment amortization	11	0
Change in unrealized gain (loss) in derivatives designated as hedging instruments	(214)	227
Interest accruals on hedging instruments	26	(8)
Total effect of fair value hedges	0	(19)
Interest rate risk on debt | Interest Expense
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) in hedged item	(239)	1,623
Discontinued hedge related basis adjustment amortization	(196)	(65)
Change in unrealized gain (loss) in derivatives designated as hedging instruments	432	(1,524)
Interest accruals on hedging instruments	(229)	47
Total effect of fair value hedges	$ (232)	$ 81