Derivative Instruments - Notional and Fair Value Position (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Derivative [Line Items]
Notional Amount	$ 420,404	$ 364,927
Asset Derivatives
Derivative assets, gross amount offset	(164)	(154)
Derivative assets	153	175
Liability Derivatives
Derivatives liabilities at fair value	(308)	(168)
Table Footnote [Abstract]
Cash collateral posted for derivative instruments	3,800	4,500
Cash collateral received for derivative instruments	101	5
Total risk management derivatives designated as hedging instruments
Derivative [Line Items]
Notional Amount	332,799	285,437
Asset Derivatives
Derivative assets, gross amount offset	(164)	(154)
Derivative assets	50	83
Liability Derivatives
Netting adjustment	3,910	4,662
Derivatives liabilities at fair value	(100)	(24)
Total risk management derivatives designated as hedging instruments | Designated as Hedging Instrument
Derivative [Line Items]
Notional Amount	48,762	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	284,037	246,579
Asset Derivatives
Derivative assets, gross	214	237
Liability Derivatives
Derivative liabilities, gross	(4,010)	(4,686)
Pay-fixed | Designated as Hedging Instrument
Derivative [Line Items]
Notional Amount	3,996	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	120,646	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	44,766	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	113,353	99,799
Asset Derivatives
Derivative assets, gross	20	1
Liability Derivatives
Derivative liabilities, gross	(3,867)	(4,525)
Basis | Not Designated as Hedging Instrument
Derivative [Line Items]
Notional Amount	41,250	41,250
Asset Derivatives
Derivative assets, gross	24	25
Liability Derivatives
Derivative liabilities, gross	0	0
Foreign currency | Not Designated as Hedging Instrument
Derivative [Line Items]
Notional Amount	306	300
Asset Derivatives
Derivative assets, gross	0	0
Liability Derivatives
Derivative liabilities, gross	(87)	(98)
Pay-fixed | Not Designated as Hedging Instrument
Derivative [Line Items]
Notional Amount	5,816	5,286
Asset Derivatives
Derivative assets, gross	164	204
Liability Derivatives
Derivative liabilities, gross	(11)	(18)
Receive-fixed | Not Designated as Hedging Instrument
Derivative [Line Items]
Notional Amount	2,666	2,136
Asset Derivatives
Derivative assets, gross	6	7
Liability Derivatives
Derivative liabilities, gross	(45)	(45)
Mortgage commitment derivatives
Derivative [Line Items]
Notional Amount	62,850	55,706
Asset Derivatives
Derivative assets, gross amount offset	0	0
Derivative assets	100	89
Liability Derivatives
Netting adjustment	0	0
Derivatives liabilities at fair value	(143)	(78)
Mortgage commitments to purchase whole loans
Derivative [Line Items]
Notional Amount	4,230	2,596
Asset Derivatives
Derivative assets	14	4
Liability Derivatives
Derivatives liabilities at fair value	(2)	(8)
Forward contracts to purchase mortgage-related securities
Derivative [Line Items]
Notional Amount	20,647	17,808
Asset Derivatives
Derivative assets	83	50
Liability Derivatives
Derivatives liabilities at fair value	(12)	(57)
Forward contracts to sell mortgage-related securities
Derivative [Line Items]
Notional Amount	37,973	35,302
Asset Derivatives
Derivative assets	3	35
Liability Derivatives
Derivatives liabilities at fair value	(129)	(13)
Credit enhancement derivatives
Derivative [Line Items]
Notional Amount	24,755	23,784
Asset Derivatives
Derivative assets	3	3
Liability Derivatives
Derivatives liabilities at fair value	$ (65)	$ (66)