Derivative Instruments - Notional and Fair Value Position (Details) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Derivative [Line Items]
Notional Amount	$ 410,604	$ 388,121
Asset Derivatives
Derivative assets, gross amount offset	(290)	(283)
Derivative assets	219	202
Liability Derivatives
Derivatives liabilities at fair value	(81)	(140)
Table Footnote [Abstract]
Cash collateral posted for derivative instruments	2,700	2,900
Cash collateral received for derivative instruments	(3)	(5)
Total risk management derivatives designated as hedging instruments
Derivative [Line Items]
Notional Amount	291,774	299,557
Asset Derivatives
Derivative assets, gross amount offset	(290)	(283)
Derivative assets	86	45
Liability Derivatives
Netting adjustment	3,026	3,200
Derivatives liabilities at fair value	(1)	(23)
Total risk management derivatives designated as hedging instruments | Designated as Hedging Instrument
Derivative [Line Items]
Notional Amount	33,240	38,541
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	258,534	261,016
Asset Derivatives
Derivative assets, gross	376	328
Liability Derivatives
Derivative liabilities, gross	(3,027)	(3,223)
Pay-fixed | Designated as Hedging Instrument
Derivative [Line Items]
Notional Amount	14,310	9,954
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	127,685	136,648
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	18,930	28,587
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	118,023	115,288
Asset Derivatives
Derivative assets, gross	60	76
Liability Derivatives
Derivative liabilities, gross	(2,858)	(3,085)
Basis | Not Designated as Hedging Instrument
Derivative [Line Items]
Notional Amount	250	250
Asset Derivatives
Derivative assets, gross	43	44
Liability Derivatives
Derivative liabilities, gross	0	0
Foreign currency | Not Designated as Hedging Instrument
Derivative [Line Items]
Notional Amount	314	316
Asset Derivatives
Derivative assets, gross	0	0
Liability Derivatives
Derivative liabilities, gross	(77)	(66)
Pay-fixed | Not Designated as Hedging Instrument
Derivative [Line Items]
Notional Amount	7,006	5,816
Asset Derivatives
Derivative assets, gross	248	195
Liability Derivatives
Derivative liabilities, gross	(22)	(12)
Receive-fixed | Not Designated as Hedging Instrument
Derivative [Line Items]
Notional Amount	5,116	2,666
Asset Derivatives
Derivative assets, gross	25	13
Liability Derivatives
Derivative liabilities, gross	(70)	(60)
Futures | Not Designated as Hedging Instrument
Derivative [Line Items]
Notional Amount	140	32
Asset Derivatives
Derivative assets, gross	0	0
Liability Derivatives
Derivative liabilities, gross	0	0
Mortgage commitment derivatives
Derivative [Line Items]
Notional Amount	90,075	60,940
Asset Derivatives
Derivative assets, gross amount offset	0	0
Derivative assets	66	112
Liability Derivatives
Netting adjustment	0	0
Derivatives liabilities at fair value	(65)	(104)
Mortgage commitments to purchase whole loans
Derivative [Line Items]
Notional Amount	4,633	2,734
Asset Derivatives
Derivative assets	4	14
Liability Derivatives
Derivatives liabilities at fair value	(7)	0
Forward contracts to purchase mortgage-related securities
Derivative [Line Items]
Notional Amount	25,675	14,264
Asset Derivatives
Derivative assets	23	98
Liability Derivatives
Derivatives liabilities at fair value	(39)	(2)
Forward contracts to sell mortgage-related securities
Derivative [Line Items]
Notional Amount	59,767	43,942
Asset Derivatives
Derivative assets	39	0
Liability Derivatives
Derivatives liabilities at fair value	(19)	(102)
Credit enhancement derivatives
Derivative [Line Items]
Notional Amount	28,755	27,624
Asset Derivatives
Derivative assets	67	45
Liability Derivatives
Derivatives liabilities at fair value	$ (15)	$ (13)