Derivative Instruments - Notional and Fair Value Position (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Derivative [Line Items]
Notional Amount	$ 448,066	$ 364,927
Asset Derivatives
Derivative assets, gross amount offset	(218)	(154)
Derivative assets	145	175
Liability Derivatives
Derivatives liabilities at fair value	(297)	(168)
Table Footnote [Abstract]
Cash collateral posted for derivative instruments	4,000	4,500
Cash collateral received for derivative instruments	26	5
Total risk management derivatives designated as hedging instruments
Derivative [Line Items]
Notional Amount	345,170	285,437
Asset Derivatives
Derivative assets, gross amount offset	(218)	(154)
Derivative assets	46	83
Liability Derivatives
Netting adjustment	4,227	4,662
Derivatives liabilities at fair value	(23)	(24)
Total risk management derivatives designated as hedging instruments | Designated as Hedging Instrument
Derivative [Line Items]
Notional Amount	30,690	38,858
Asset Derivatives
Derivative assets, gross	0	0
Liability Derivatives
Derivative liabilities, gross	0	0
Total risk management derivatives designated as hedging instruments | Not Designated as Hedging Instrument
Derivative [Line Items]
Notional Amount	314,480	246,579
Asset Derivatives
Derivative assets, gross	264	237
Liability Derivatives
Derivative liabilities, gross	(4,250)	(4,686)
Pay-fixed | Designated as Hedging Instrument
Derivative [Line Items]
Notional Amount	3,371	5,582
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	134,023	97,808
Asset Derivatives
Derivative assets, gross	0	0
Liability Derivatives
Derivative liabilities, gross	0	0
Receive-fixed | Designated as Hedging Instrument
Derivative [Line Items]
Notional Amount	27,319	33,276
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	171,397	99,799
Asset Derivatives
Derivative assets, gross	43	1
Liability Derivatives
Derivative liabilities, gross	(4,099)	(4,525)
Basis | Not Designated as Hedging Instrument
Derivative [Line Items]
Notional Amount	250	41,250
Asset Derivatives
Derivative assets, gross	36	25
Liability Derivatives
Derivative liabilities, gross	0	0
Foreign currency | Not Designated as Hedging Instrument
Derivative [Line Items]
Notional Amount	315	300
Asset Derivatives
Derivative assets, gross	0	0
Liability Derivatives
Derivative liabilities, gross	(88)	(98)
Pay-fixed | Not Designated as Hedging Instrument
Derivative [Line Items]
Notional Amount	5,816	5,286
Asset Derivatives
Derivative assets, gross	176	204
Liability Derivatives
Derivative liabilities, gross	(12)	(18)
Receive-fixed | Not Designated as Hedging Instrument
Derivative [Line Items]
Notional Amount	2,666	2,136
Asset Derivatives
Derivative assets, gross	9	7
Liability Derivatives
Derivative liabilities, gross	(51)	(45)
Futures | Not Designated as Hedging Instrument
Derivative [Line Items]
Notional Amount	13	0
Asset Derivatives
Derivative assets, gross	0	0
Liability Derivatives
Derivative liabilities, gross	0	0
Mortgage commitment derivatives
Derivative [Line Items]
Notional Amount	76,532	55,706
Asset Derivatives
Derivative assets, gross amount offset	0	0
Derivative assets	52	89
Liability Derivatives
Netting adjustment	0	0
Derivatives liabilities at fair value	(204)	(78)
Mortgage commitments to purchase whole loans
Derivative [Line Items]
Notional Amount	4,495	2,596
Asset Derivatives
Derivative assets	1	4
Liability Derivatives
Derivatives liabilities at fair value	(14)	(8)
Forward contracts to purchase mortgage-related securities
Derivative [Line Items]
Notional Amount	24,325	17,808
Asset Derivatives
Derivative assets	19	50
Liability Derivatives
Derivatives liabilities at fair value	(88)	(57)
Forward contracts to sell mortgage-related securities
Derivative [Line Items]
Notional Amount	47,712	35,302
Asset Derivatives
Derivative assets	32	35
Liability Derivatives
Derivatives liabilities at fair value	(102)	(13)
Credit enhancement derivatives
Derivative [Line Items]
Notional Amount	26,364	23,784
Asset Derivatives
Derivative assets	47	3
Liability Derivatives
Derivatives liabilities at fair value	$ (70)	$ (66)