Loans Held for Sale - Summary of Activity in Balance of Loans Held for Sale, at Fair Value (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Receivables [Abstract]
Principal amount outstanding on loans held for sale	$ 2,008.5	$ 2,008.5	$ 1,401.2
Premium (discount) balance on loans held for sale	(97.9)	(97.9)	(91.6)
Fair value adjustment to loans held for sale	(18.9)	(18.9)	(19.4)
Mortgages, held-for-sale	1,891.7	1,891.7	1,290.2
Movement In Loans Held For Sale At Fair Value [Roll Forward]
Beginning balance		1,290.2	674.2	$ 617.8
Originations and purchases		25,436.7	17,811.4	12,797.5
Proceeds from sales		(24,344.1)	(16,857.8)	(12,450.8)
Principal collections		(188.6)	(102.1)	(87.5)
Transfer from loans held for investment to loans held for sale	0.5	13.1	4.8	6.1
Transfer of Portfolio Loans and Leases to Held-for-sale			4.8	6.1
Transfer Of Portfolio Loans To Receivables		(70.5)	(32.9)	(33.2)
Real estate owned (Other assets)		(61.9)	(26.8)	(19.4)
Transfer Of Portfolio Loans To Real Estate Owned		(61.9)	(26.8)	(19.4)
Transfer To Receivables		(70.5)	(32.9)	(33.2)
Capitalization of advances on Ginnie Mae modifications		17.5	9.3	6.4
Fair value gain (loss) on loans held for sale		(234.3)	(216.2)	(165.7)
Other		33.6	26.1	2.8
Ending balance	1,891.7	1,891.7	1,290.2	674.2
Accounts, Notes, Loans and Financing Receivable [Line Items]
Mortgages, held-for-sale	1,891.7	1,891.7	1,290.2
Loans Held-for-sale, Fair Value Disclosure	1,891.7	1,891.7	1,290.2	674.2
Transfer Of Portfolio Loans To Real Estate Owned		61.9	26.8	19.4
Transfer Of Portfolio Loans To Receivables		(70.5)	(32.9)	$ (33.2)
GSE Loans
Movement In Loans Held For Sale At Fair Value [Roll Forward]
Beginning balance		610.8
Ending balance	482.8	482.8	610.8
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Held-for-sale, Fair Value Disclosure	482.8	482.8	610.8
Government Forward Loans
Movement In Loans Held For Sale At Fair Value [Roll Forward]
Beginning balance		215.5
Ending balance	550.0	550.0	215.5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Held-for-sale, Fair Value Disclosure	550.0	550.0	215.5
Repurchased Ginnie Mae Loans
Movement In Loans Held For Sale At Fair Value [Roll Forward]
Beginning balance		26.1
Ending balance	31.2	31.2	26.1
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Held-for-sale, Fair Value Disclosure	31.2	31.2	26.1
Reverse Loans
Movement In Loans Held For Sale At Fair Value [Roll Forward]
Beginning balance		432.4
Ending balance	722.2	722.2	432.4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Held-for-sale, Fair Value Disclosure	722.2	722.2	432.4
Residential Mortgage Backed Securities
Movement In Loans Held For Sale At Fair Value [Roll Forward]
Beginning balance		5.3
Ending balance	105.5	105.5	5.3
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Held-for-sale, Fair Value Disclosure	$ 105.5	$ 105.5	$ 5.3