Derivative Instruments - Schedule of Notional and Fair Value Position (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Derivative [Line Items]
Notional amount	$ 388,121.0	$ 364,927.0
Asset Derivatives
Netting Adjustment	(283.0)	(154.0)
Derivative assets	202.0	175.0
Liability Derivatives
Derivatives liabilities at fair value	(140.0)	(168.0)
Table Footnote
Cash collateral posted for derivative instruments	2,900.0	4,500.0
Cash collateral received for derivative instruments	5.0	5.0
Total risk management derivatives portfolio
Derivative [Line Items]
Notional amount	299,557.0	285,437.0
Asset Derivatives
Netting Adjustment	(283.0)	(154.0)
Derivative assets	45.0	83.0
Liability Derivatives
Netting adjustment	3,200.0	4,662.0
Derivatives liabilities at fair value	(23.0)	(24.0)
Total risk management derivatives portfolio | Risk management derivatives designated as hedging instruments:
Derivative [Line Items]
Notional amount	38,541.0	38,858.0
Asset Derivatives
Derivative assets, gross	0.0	0.0
Liability Derivatives
Derivative liabilities, gross	0.0	0.0
Total risk management derivatives portfolio | Risk management derivatives not designated as hedging instruments:
Derivative [Line Items]
Notional amount	261,016.0	246,579.0
Asset Derivatives
Derivative assets, gross	328.0	237.0
Liability Derivatives
Derivative liabilities, gross	(3,223.0)	(4,686.0)
Pay-fixed | Risk management derivatives designated as hedging instruments:
Derivative [Line Items]
Notional amount	9,954.0	5,582.0
Asset Derivatives
Derivative assets, gross	0.0	0.0
Liability Derivatives
Derivative liabilities, gross	0.0	0.0
Pay-fixed | Risk management derivatives not designated as hedging instruments:
Derivative [Line Items]
Notional amount	136,648.0	97,808.0
Asset Derivatives
Derivative assets, gross	0.0	0.0
Liability Derivatives
Derivative liabilities, gross	0.0	0.0
Receive-fixed | Risk management derivatives designated as hedging instruments:
Derivative [Line Items]
Notional amount	28,587.0	33,276.0
Asset Derivatives
Derivative assets, gross	0.0	0.0
Liability Derivatives
Derivative liabilities, gross	0.0	0.0
Receive-fixed | Risk management derivatives not designated as hedging instruments:
Derivative [Line Items]
Notional amount	115,288.0	99,799.0
Asset Derivatives
Derivative assets, gross	76.0	1.0
Liability Derivatives
Derivative liabilities, gross	(3,085.0)	(4,525.0)
Basis | Risk management derivatives not designated as hedging instruments:
Derivative [Line Items]
Notional amount	250.0	41,250.0
Asset Derivatives
Derivative assets, gross	44.0	25.0
Liability Derivatives
Derivative liabilities, gross	0.0	0.0
Foreign currency | Risk management derivatives not designated as hedging instruments:
Derivative [Line Items]
Notional amount	316.0	300.0
Asset Derivatives
Derivative assets, gross	0.0	0.0
Liability Derivatives
Derivative liabilities, gross	(66.0)	(98.0)
Pay-fixed swaption | Risk management derivatives not designated as hedging instruments:
Derivative [Line Items]
Notional amount	5,816.0	5,286.0
Asset Derivatives
Derivative assets, gross	195.0	204.0
Liability Derivatives
Derivative liabilities, gross	(12.0)	(18.0)
Receive-fixed swaption | Risk management derivatives not designated as hedging instruments:
Derivative [Line Items]
Notional amount	2,666.0	2,136.0
Asset Derivatives
Derivative assets, gross	13.0	7.0
Liability Derivatives
Derivative liabilities, gross	(60.0)	(45.0)
Futures | Risk management derivatives not designated as hedging instruments:
Derivative [Line Items]
Notional amount	32.0	0.0
Asset Derivatives
Derivative assets, gross	0.0	0.0
Liability Derivatives
Derivative liabilities, gross	0.0	0.0
Mortgage commitment derivatives
Derivative [Line Items]
Notional amount	60,940.0	55,706.0
Asset Derivatives
Netting Adjustment	0.0	0.0
Derivative assets	112.0	89.0
Liability Derivatives
Netting adjustment	0.0	0.0
Derivatives liabilities at fair value	(104.0)	(78.0)
Mortgage commitments to purchase whole loans
Derivative [Line Items]
Notional amount	2,734.0	2,596.0
Asset Derivatives
Derivative assets	14.0	4.0
Liability Derivatives
Derivatives liabilities at fair value	0.0	(8.0)
Forward contracts to purchase mortgage-related securities
Derivative [Line Items]
Notional amount	14,264.0	17,808.0
Asset Derivatives
Derivative assets	98.0	50.0
Liability Derivatives
Derivatives liabilities at fair value	(2.0)	(57.0)
Forward contracts to sell mortgage-related securities
Derivative [Line Items]
Notional amount	43,942.0	35,302.0
Asset Derivatives
Derivative assets	0.0	35.0
Liability Derivatives
Derivatives liabilities at fair value	(102.0)	(13.0)
Credit enhancement derivatives
Derivative [Line Items]
Notional amount	27,624.0	23,784.0
Asset Derivatives
Derivative assets	45.0	3.0
Liability Derivatives
Derivatives liabilities at fair value	$ (13.0)	$ (66.0)