Loans Held for Sale - Fair Value - Schedule of Loans Held for Sale Fair Value (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2025	Mar. 31, 2024
Movement In Loans Held For Sale At Fair Value [Roll Forward]
Beginning balance	$ 1,290.2	$ 674.2
Originations and purchases	4,273.3	2,988.9
Proceeds from sales	(4,082.6)	(2,581.0)
Principal collections	(32.0)	(23.1)
Loans held for investment, at fair value	3.1	1.0
Receivables	(20.5)	(10.6)
REO (Other assets)	(12.3)	(3.0)
Advances (incl. capitalization upon Ginnie Mae modifications)	4.8	2.1
Fair value gain (loss) on loans held for sale, at fair value (1)	(35.4)	(27.5)
Other (2)	13.6	4.7
Ending balance	1,402.2	1,025.7
Principal amount outstanding on loans held for sale	1,491.4	1,401.2
Premium (discount) balance on loans held for sale	(76.4)	(91.6)
Fair value adjustment to loans held for sale	(12.8)	(19.4)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Held-for-sale, Fair Value Disclosure	1,402.2	$ 1,025.7
GSE loans
Movement In Loans Held For Sale At Fair Value [Roll Forward]
Beginning balance	610.8
Ending balance	722.6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Held-for-sale, Fair Value Disclosure	722.6
Government- Forward loans
Movement In Loans Held For Sale At Fair Value [Roll Forward]
Beginning balance	215.5
Ending balance	191.9
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Held-for-sale, Fair Value Disclosure	191.9
Repurchased Ginnie Mae Loans
Movement In Loans Held For Sale At Fair Value [Roll Forward]
Beginning balance	26.1
Ending balance	38.6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Held-for-sale, Fair Value Disclosure	38.6
Reverse Loans
Movement In Loans Held For Sale At Fair Value [Roll Forward]
Beginning balance	432.4
Ending balance	442.6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Held-for-sale, Fair Value Disclosure	442.6
Other residential mortgage loans
Movement In Loans Held For Sale At Fair Value [Roll Forward]
Beginning balance	5.3
Ending balance	6.4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Held-for-sale, Fair Value Disclosure	$ 6.4

Capitalization of advances on Ginnie Mae modifications.

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Fair value adjustment to loans held for sale

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Represents amount of addition or reductions in principal on mortgage loans held for sale other than foreclosures, costs of mortgages sold, and amortization of premium during the reporting period.

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Premium (discount) balance on loans held for sale

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Principal amount outstanding on loans held for sale

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Value of loans held for sale at fair value in the entity's portfolio transferred to real estate owned in non-cash transactions.

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The increase (decrease) during the reporting period in the value of loans or securitized loans that are held with the intention to sell in the near future.

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Fair value portion of loans held-for-sale including, but not limited to, mortgage loans and finance receivables.

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The amount of cash paid for the origination of mortgages that are held for sale.

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Cash inflow related to a loan origination (the process when securing a mortgage for a piece of real property), lease origination, and principal collections.

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The cash inflow from sales of loans that are secured with real estate mortgages and are held with the intention to resell in the near future.

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Value of loans and leases held in the entity's portfolio transferred to loans and leases held-for-sale in noncash transactions.

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