MORTGAGE SERVICING RIGHTS - Presentation of Activity Related to MSR (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Servicing Asset at Fair Value, Amount [Roll Forward]
Fair value, beginning of period	$ 100,895	$ 378,078
Changes in valuation inputs or assumptions	27,673	(79,224)
Other changes, including realization of expected cash flows	(15,488)	(18,296)
Fair value, end of period	$ 113,080	$ 280,558