Derivative Instruments - Schedule of Notional and Fair Value Position (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Derivative [Line Items]
Notional amount	$ 366,384	$ 739,179
Asset Derivatives
Netting adjustment	(237)	(905)
Derivative assets	171	1,225
Liability Derivatives
Netting adjustment	1,173	995
Derivatives liabilities at fair value	(233)	(1,495)
Table Footnote
Cash collateral posted for derivative instruments	966	658
Cash collateral received for derivative instruments	30	568
Total risk management derivatives portfolio
Derivative [Line Items]
Notional amount	164,742	302,790
Asset Derivatives
Netting adjustment	(237)	(905)
Derivative assets	2	57
Liability Derivatives
Netting adjustment	1,173	995
Derivatives liabilities at fair value	(15)	(20)
Total risk management derivatives portfolio | Not Designated as Hedging Instrument
Derivative [Line Items]
Notional amount	119,709	302,790
Asset Derivatives
Derivative assets, gross	239	962
Liability Derivatives
Derivative liabilities, gross	(1,188)	(1,015)
Total risk management derivatives portfolio | Fair Value Hedging | Designated as Hedging Instrument
Derivative [Line Items]
Notional amount	45,033	0
Asset Derivatives
Derivative assets, gross	0	0
Liability Derivatives
Derivative liabilities, gross	0	0
Pay-fixed | Not Designated as Hedging Instrument
Derivative [Line Items]
Notional amount	56,817	99,822
Asset Derivatives
Derivative assets, gross	0	3
Liability Derivatives
Derivative liabilities, gross	0	(684)
Pay-fixed | Fair Value Hedging | Designated as Hedging Instrument
Derivative [Line Items]
Notional amount	4,347	0
Asset Derivatives
Derivative assets, gross	0	0
Liability Derivatives
Derivative liabilities, gross	0	0
Receive-fixed | Not Designated as Hedging Instrument
Derivative [Line Items]
Notional amount	56,874	126,234
Asset Derivatives
Derivative assets, gross	0	314
Liability Derivatives
Derivative liabilities, gross	(1,131)	(137)
Receive-fixed | Fair Value Hedging | Designated as Hedging Instrument
Derivative [Line Items]
Notional amount	40,686	0
Asset Derivatives
Derivative assets, gross	0	0
Liability Derivatives
Derivative liabilities, gross	0	0
Basis | Not Designated as Hedging Instrument
Derivative [Line Items]
Notional amount	250	250
Asset Derivatives
Derivative assets, gross	152	203
Liability Derivatives
Derivative liabilities, gross	0	0
Foreign currency | Not Designated as Hedging Instrument
Derivative [Line Items]
Notional amount	336	476
Asset Derivatives
Derivative assets, gross	25	59
Liability Derivatives
Derivative liabilities, gross	(34)	(60)
Pay-fixed swaption | Not Designated as Hedging Instrument
Derivative [Line Items]
Notional amount	4,341	7,555
Asset Derivatives
Derivative assets, gross	52	37
Liability Derivatives
Derivative liabilities, gross	(2)	(118)
Receive-fixed swaption | Not Designated as Hedging Instrument
Derivative [Line Items]
Notional amount	1,091	4,055
Asset Derivatives
Derivative assets, gross	10	346
Liability Derivatives
Derivative liabilities, gross	(21)	(16)
Futures | Not Designated as Hedging Instrument
Derivative [Line Items]
Notional amount	0	64,398
Asset Derivatives
Derivative assets, gross	0	0
Liability Derivatives
Derivative liabilities, gross	0	0
Mortgage commitment derivatives
Derivative [Line Items]
Notional amount	182,386	408,192
Asset Derivatives
Netting adjustment	0	0
Derivative assets	169	989
Liability Derivatives
Netting adjustment	0	0
Derivatives liabilities at fair value	(197)	(1,426)
Mortgage commitments to purchase whole loans
Derivative [Line Items]
Notional amount	13,192	35,343
Asset Derivatives
Derivative assets	17	145
Liability Derivatives
Derivatives liabilities at fair value	(5)	0
Forward contracts to purchase mortgage-related securities
Derivative [Line Items]
Notional amount	58,021	144,822
Asset Derivatives
Derivative assets	83	844
Liability Derivatives
Derivatives liabilities at fair value	(34)	0
Forward contracts to sell mortgage-related securities
Derivative [Line Items]
Notional amount	111,173	228,027
Asset Derivatives
Derivative assets	69	0
Liability Derivatives
Derivatives liabilities at fair value	(158)	(1,426)
Credit enhancement derivatives
Derivative [Line Items]
Notional amount	19,256	28,197
Asset Derivatives
Derivative assets	0	179
Liability Derivatives
Derivatives liabilities at fair value	$ (21)	$ (49)