MORTGAGE SERVICING RIGHTS AND MSR FINANCING RECEIVABLES - Summary of Reserve For Servicer Advances (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Servicer Advances Reserve [Roll Forward]
Beginning balance	$ 22,849	$ 1,680
Caliber acquisition (Note 3)	15,068
Provision	11,560	21,619
Write-offs	(17,355)	(450)
Ending balance	$ 32,122	$ 22,849