Derivative Financial Instruments - Derivative Instruments (Details) - USD ($) $ in Millions	9 Months Ended
Sep. 30, 2021	Sep. 30, 2020
Assets
Derivatives, Fair Value [Line Items]
Outstanding Notional	$ 19,824	$ 27,636
Fair Value	234	475
Gains/(Losses)	(255)	322
Assets \| Loan sale commitments
Derivatives, Fair Value [Line Items]
Outstanding Notional	1,435	1,908
Fair Value	29	75
Gains/(Losses)	(73)	43
Assets \| IRLCs
Derivatives, Fair Value [Line Items]
Outstanding Notional	6,167	10,967
Fair Value	167	414
Gains/(Losses)	(247)	279
Assets \| LPCs
Derivatives, Fair Value [Line Items]
Outstanding Notional	887	5,217
Fair Value	6	38
Gains/(Losses)	(32)	26
Assets \| Forward MBS trades
Derivatives, Fair Value [Line Items]
Outstanding Notional	12,770	11,452
Fair Value	61	23
Gains/(Losses)	24	17
Liabilities
Derivatives, Fair Value [Line Items]
Outstanding Notional	9,486	16,574
Derivative financial instruments	48	44
Gains/(Losses)	(109)	29
Liabilities \| IRLCs
Derivatives, Fair Value [Line Items]
Outstanding Notional	25	2
Derivative financial instruments	0	0
Gains/(Losses)	0	0
Liabilities \| LPCs
Derivatives, Fair Value [Line Items]
Outstanding Notional	2,208	598
Derivative financial instruments	13	2
Gains/(Losses)	12	(1)
Liabilities \| Forward MBS trades
Derivatives, Fair Value [Line Items]
Outstanding Notional	6,553	15,974
Derivative financial instruments	23	42
Gains/(Losses)	(133)	$ 30
Liabilities \| Swap futures
Derivatives, Fair Value [Line Items]
Outstanding Notional	700
Derivative financial instruments	12
Gains/(Losses)	$ 12

Nominal or face amount used to calculate payments on the derivative asset.

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Nominal or face amount used to calculate payments on the derivative liability.

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