Derivative Financial Instruments - Derivative Instruments (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Dec. 31, 2024
Loan sale commitments
Derivatives, Fair Value [Line Items]
Gain/(Loss)	$ 2	$ 11
Interest Rate Lock Commitments, Assets
Derivatives, Fair Value [Line Items]
Gain/(Loss)	19	10
us-gaap_InterestRateLockCommitmentsMember
Derivatives, Fair Value [Line Items]
Gain/(Loss)	0	0
Loan Purchase Commitments, Assets
Derivatives, Fair Value [Line Items]
Gain/(Loss)	7	(1)
Loan Purchase Commitments, Liabilities
Derivatives, Fair Value [Line Items]
Gain/(Loss)	6	(1)
Forward Contracts, Assets
Derivatives, Fair Value [Line Items]
Gain/(Loss)	232	15
Forward Contracts, Liabilities
Derivatives, Fair Value [Line Items]
Gain/(Loss)	(186)	(87)
Treasury futures, Liabilities
Derivatives, Fair Value [Line Items]
Gain/(Loss)		(96)
Derivative financial instruments, liabilities
Derivatives, Fair Value [Line Items]
Gain/(Loss)	(180)	(184)
Derivative financial instruments, assets
Derivatives, Fair Value [Line Items]
Gain/(Loss)	337	(26)
Treasury futures | Recurring Fair Value Measurements
Derivatives, Fair Value [Line Items]
Fair Value			$ (59)
Interest Rate Lock Commitments [Member] | Recurring Fair Value Measurements
Derivatives, Fair Value [Line Items]
Fair Value	41		22
Forward Contracts [Member] | Recurring Fair Value Measurements
Derivatives, Fair Value [Line Items]
Fair Value	118		18
Fair Value	(34)		(95)
Treasury futures, Assets [Member]
Derivatives, Fair Value [Line Items]
Gain/(Loss)	79	(50)
Treasury futures, Assets [Member] | Recurring Fair Value Measurements
Derivatives, Fair Value [Line Items]
Fair Value	79
Loan Purchase Commitments [Member] | Recurring Fair Value Measurements
Derivatives, Fair Value [Line Items]
Fair Value	12		6
Fair Value	(1)		$ (7)
Assets
Derivatives, Fair Value [Line Items]
Outstanding Notional	15,344	6,574
Fair Value	250	102
Assets | Loan sale commitments
Derivatives, Fair Value [Line Items]
Outstanding Notional	845	652
Fair Value	14	22
Assets | Treasury futures
Derivatives, Fair Value [Line Items]
Outstanding Notional	4,272	3,432
Fair Value	79	62
Assets | Interest Rate Lock Commitments [Member]
Derivatives, Fair Value [Line Items]
Outstanding Notional	1,106	1,029
Fair Value	41	31
Assets | Forward Contracts [Member]
Derivatives, Fair Value [Line Items]
Outstanding Notional	8,369	1,789
Fair Value	118	7
Assets | Loan Purchase Commitments [Member]
Derivatives, Fair Value [Line Items]
Outstanding Notional	1,597	324
Fair Value	12	2
Liabilities
Derivatives, Fair Value [Line Items]
Outstanding Notional	4,416	5,772
Fair Value	(35)	(13)
Liabilities | Treasury futures
Derivatives, Fair Value [Line Items]
Outstanding Notional		470
Fair Value		(3)
Liabilities | Interest Rate Lock Commitments [Member]
Derivatives, Fair Value [Line Items]
Outstanding Notional	3	25
Fair Value	0	0
Liabilities | Forward Contracts [Member]
Derivatives, Fair Value [Line Items]
Outstanding Notional	4,226	4,797
Fair Value		(8)
Liabilities | Loan Purchase Commitments [Member]
Derivatives, Fair Value [Line Items]
Outstanding Notional	$ 187	480
Fair Value		$ (2)