MORTGAGE SERVICING RIGHTS - Presentation of Activity Related to MSR (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Servicing Asset at Fair Value, Amount [Roll Forward]
Fair value, beginning of period	$ 425,328	$ 599,014	$ 557,813	$ 580,860
Changes in valuation inputs or assumptions	(17,312)	(19,913)	(116,150)	(61,011)
Other changes, including realization of expected cash flows	(21,965)	9,732	(55,612)	68,984
Fair value, end of period	$ 386,051	$ 588,833	$ 386,051	$ 588,833