SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Summary of Goodwill (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Goodwill [Roll Forward]
Beginning balance	$ 29,468	$ 29,468
Goodwill acquired	55,731	0
Accumulated impairment loss	0	0
Other adjustments	0	0
Ending balance	85,199	29,468
Origination
Goodwill [Roll Forward]
Beginning balance	11,836	11,836
Goodwill acquired	0	0
Accumulated impairment loss	0	0
Other adjustments	0	0
Ending balance	11,836	11,836
Servicing
Goodwill [Roll Forward]
Beginning balance	12,540	12,540
Goodwill acquired	0	0
Accumulated impairment loss	0	0
Other adjustments	0	0
Ending balance	12,540	12,540
MSR Related Investments
Goodwill [Roll Forward]
Beginning balance	5,092	5,092
Goodwill acquired	0	0
Accumulated impairment loss	0	0
Other adjustments	0	0
Ending balance	5,092	5,092
Mortgage Loans Receivable
Goodwill [Roll Forward]
Beginning balance	0	0
Goodwill acquired	55,731	0
Accumulated impairment loss	0	0
Other adjustments	0	0
Ending balance	$ 55,731	$ 0