MORTGAGE SERVICING RIGHTS AND MSR FINANCING RECEIVABLES - Summary of the Geographic Distribution of the Underlying Residential Mortgage Loans of the MSRs (Details) - MSRs - Mortgage Loans	Sep. 30, 2025	Dec. 31, 2024
Schedule of MSRs [Line Items]
Percentage of Total Outstanding Unpaid Principal Amount	100.00%	100.00%
California
Schedule of MSRs [Line Items]
Percentage of Total Outstanding Unpaid Principal Amount	16.00%	16.50%
Florida
Schedule of MSRs [Line Items]
Percentage of Total Outstanding Unpaid Principal Amount	8.10%	8.20%
Texas
Schedule of MSRs [Line Items]
Percentage of Total Outstanding Unpaid Principal Amount	6.70%	6.60%
New York
Schedule of MSRs [Line Items]
Percentage of Total Outstanding Unpaid Principal Amount	5.70%	5.70%
Washington
Schedule of MSRs [Line Items]
Percentage of Total Outstanding Unpaid Principal Amount	5.10%	5.20%
New Jersey
Schedule of MSRs [Line Items]
Percentage of Total Outstanding Unpaid Principal Amount	4.00%	4.10%
Virginia
Schedule of MSRs [Line Items]
Percentage of Total Outstanding Unpaid Principal Amount	3.80%	3.70%
Maryland
Schedule of MSRs [Line Items]
Percentage of Total Outstanding Unpaid Principal Amount	3.40%	3.40%
Illinois
Schedule of MSRs [Line Items]
Percentage of Total Outstanding Unpaid Principal Amount	3.20%	3.30%
Georgia
Schedule of MSRs [Line Items]
Percentage of Total Outstanding Unpaid Principal Amount	3.10%	3.10%
Other U.S.
Schedule of MSRs [Line Items]
Percentage of Total Outstanding Unpaid Principal Amount	40.90%	40.20%