Derivative Financial Instruments - Derivative Instruments (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Loan sale commitments
Derivatives, Fair Value [Line Items]
Gain/(Loss)	$ 0	$ 4
Interest Rate Lock Commitments, Assets
Derivatives, Fair Value [Line Items]
Gain/(Loss)	16	6
us-gaap_InterestRateLockCommitmentsMember
Derivatives, Fair Value [Line Items]
Gain/(Loss)	0	0
Loan Purchase Commitments, Assets
Derivatives, Fair Value [Line Items]
Gain/(Loss)	2	(1)
Loan Purchase Commitments, Liabilities
Derivatives, Fair Value [Line Items]
Gain/(Loss)	5	0
Forward Contracts, Assets
Derivatives, Fair Value [Line Items]
Gain/(Loss)	121	(2)
Forward Contracts, Liabilities
Derivatives, Fair Value [Line Items]
Gain/(Loss)	(67)	(28)
Treasury futures, Liabilities
Derivatives, Fair Value [Line Items]
Gain/(Loss)	53	0
Derivative financial instruments, liabilities
Derivatives, Fair Value [Line Items]
Gain/(Loss)	(9)	(28)
Derivative financial instruments, assets
Derivatives, Fair Value [Line Items]
Gain/(Loss)	194	(92)
Treasury futures, Assets [Member]
Derivatives, Fair Value [Line Items]
Gain/(Loss)	55	(95)
Assets
Derivatives, Fair Value [Line Items]
Outstanding Notional	14,252	5,779
Fair Value	115	55
Assets | Loan sale commitments
Derivatives, Fair Value [Line Items]
Outstanding Notional	1,128	399
Fair Value	13	15
Assets | Forward MBS trades
Derivatives, Fair Value [Line Items]
Outstanding Notional	1,138	244
Fair Value	8	1
Assets | Treasury futures
Derivatives, Fair Value [Line Items]
Outstanding Notional	4,140	2,969
Fair Value	54	18
Assets | Interest Rate Lock Commitments [Member]
Derivatives, Fair Value [Line Items]
Outstanding Notional	997	765
Fair Value	38	27
Assets | Forward Contracts [Member]
Derivatives, Fair Value [Line Items]
Outstanding Notional	7,977	1,801
Fair Value	15	9
Liabilities
Derivatives, Fair Value [Line Items]
Outstanding Notional	4,411	4,366
Fair Value	(19)	(11)
Liabilities | Forward MBS trades
Derivatives, Fair Value [Line Items]
Outstanding Notional	474	91
Fair Value		0
Liabilities | Treasury futures
Derivatives, Fair Value [Line Items]
Outstanding Notional	290	343
Fair Value	(1)	(1)
Liabilities | Interest Rate Lock Commitments [Member]
Derivatives, Fair Value [Line Items]
Outstanding Notional	7	2
Fair Value	0	0
Liabilities | Forward Contracts [Member]
Derivatives, Fair Value [Line Items]
Outstanding Notional	$ 3,640	3,930
Fair Value		$ (10)