Mortgage Servicing - Schedule of Composition of Servicing UPB (Details) - USD ($) $ in Millions	Sep. 30, 2026	Jun. 30, 2026	Dec. 31, 2025	Jun. 30, 2025	Dec. 31, 2024
Servicing Assets at Fair Value [Line Items]
MSRs, at fair value	$ 3,360.6	$ 3,208.8	$ 2,825.3	$ 2,632.6	$ 2,466.3
Assets serviced	199,800.0		191,100.0
UPB of loans transferred	75,310.2		64,876.2
MSR related financing liabilities, at fair value	613.1		842.0
Financing Liability Mortgage Servicing Rights Pledged [Member]
Servicing Assets at Fair Value [Line Items]
MSR related financing liabilities, at fair value	346.8		573.2
Original Rights to Mortgage Servicing Rights Agreements \| Financing Liability Mortgage Servicing Rights Pledged [Member]
Servicing Assets at Fair Value [Line Items]
MSR related financing liabilities, at fair value	38.5
Owned MSRs
Servicing Assets at Fair Value [Line Items]
MSRs, at fair value	3,010.7		2,244.3
Assets serviced	177,200.0		152,500.0
Financing Liability Excess Servicing Spread [Member]
Servicing Assets at Fair Value [Line Items]
MSRs, at fair value	363.8		373.5
Transferred MSR, Subject To Pledged Liability
Servicing Assets at Fair Value [Line Items]
MSRs, at fair value	349.9		581.0
Assets serviced	22,600.0		$ 38,600.0
Transferred MSR, Subject To Pledged Liability \| Rithm Capital Corp
Servicing Assets at Fair Value [Line Items]
Assets serviced	$ 3,300.0