Fair Value Measurements - Measured on a Recurring Basis (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Assets
Mortgage loans held for sale	$ 7,939	$ 5,720
Liabilities
Mortgage servicing rights financing	20	33
Recurring Fair Value Measurements
Assets
Mortgage loans held for sale	7,939	5,720
Forward mortgage servicing rights	3,666	2,703
Equity securities	58
Liabilities
Mortgage servicing rights financing	20	33
Excess spread financing	822	934
Recurring Fair Value Measurements \| IRLCs
Assets
Derivative financial instruments	167	414
Recurring Fair Value Measurements \| LPCs
Assets
Derivative financial instruments	6	38
Liabilities
Derivative financial instruments	13	1
Recurring Fair Value Measurements \| Forward MBS trades
Assets
Derivative financial instruments	61	37
Liabilities
Derivative financial instruments	23	156
Recurring Fair Value Measurements \| Swap futures
Liabilities
Derivative financial instruments	12
Recurring Fair Value Measurements \| Level 1
Assets
Mortgage loans held for sale	0	0
Forward mortgage servicing rights	0	0
Equity securities	8
Liabilities
Mortgage servicing rights financing	0	0
Excess spread financing	0	0
Recurring Fair Value Measurements \| Level 1 \| IRLCs
Assets
Derivative financial instruments	0	0
Recurring Fair Value Measurements \| Level 1 \| LPCs
Assets
Derivative financial instruments	0	0
Liabilities
Derivative financial instruments	0	0
Recurring Fair Value Measurements \| Level 1 \| Forward MBS trades
Assets
Derivative financial instruments	0	0
Liabilities
Derivative financial instruments	0	0
Recurring Fair Value Measurements \| Level 1 \| Swap futures
Liabilities
Derivative financial instruments	0
Recurring Fair Value Measurements \| Level 2
Assets
Mortgage loans held for sale	7,939	5,720
Forward mortgage servicing rights	0	0
Equity securities	0
Liabilities
Mortgage servicing rights financing	0	0
Excess spread financing	0	0
Recurring Fair Value Measurements \| Level 2 \| IRLCs
Assets
Derivative financial instruments	0	0
Recurring Fair Value Measurements \| Level 2 \| LPCs
Assets
Derivative financial instruments	0	0
Liabilities
Derivative financial instruments	0	0
Recurring Fair Value Measurements \| Level 2 \| Forward MBS trades
Assets
Derivative financial instruments	61	37
Liabilities
Derivative financial instruments	23	156
Recurring Fair Value Measurements \| Level 2 \| Swap futures
Liabilities
Derivative financial instruments	12
Recurring Fair Value Measurements \| Level 3
Assets
Mortgage loans held for sale	0	0
Forward mortgage servicing rights	3,666	2,703
Equity securities	50
Liabilities
Mortgage servicing rights financing	20	33
Excess spread financing	822	934
Recurring Fair Value Measurements \| Level 3 \| IRLCs
Assets
Derivative financial instruments	167	414
Recurring Fair Value Measurements \| Level 3 \| LPCs
Assets
Derivative financial instruments	6	38
Liabilities
Derivative financial instruments	13	1
Recurring Fair Value Measurements \| Level 3 \| Forward MBS trades
Assets
Derivative financial instruments	0	0
Liabilities
Derivative financial instruments	0	$ 0
Recurring Fair Value Measurements \| Level 3 \| Swap futures
Liabilities
Derivative financial instruments	$ 0

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Mortgage Servicing Rights Liability Resulting from Sale or Securitization of Servicer Advances, Rights not Accounted for as a Sale

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- Definition

Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

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Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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- Definition

Fair value portion of mortgage loans held-for-sale.

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- Definition

Fair value of an asset representing net future revenue from contractually specified servicing fees, late charges, and other ancillary revenues, in excess of future costs related to servicing arrangements.

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