SERVICING RIGHTS, AT FAIR VALUE - Unpaid Principal of Servicing Portfolio (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Servicing Assets at Fair Value [Line Items]
Total portfolio	$ 155,217,012	$ 162,112,965
Percentage of servicing portfolio in forbearance resulting from COVID-19	0.40%	0.60%
Current loans
Servicing Assets at Fair Value [Line Items]
Total portfolio	$ 153,367,435	$ 160,302,966
Loans 30 - 89 days delinquent
Servicing Assets at Fair Value [Line Items]
Total portfolio	520,963	504,467
Loans 90 or more days delinquent or in foreclosure
Servicing Assets at Fair Value [Line Items]
Total portfolio	$ 1,328,614	$ 1,305,532