MORTGAGE SERVICING RIGHTS - Presentation of Activity Related to MSR (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Servicing Asset at Fair Value, Amount [Roll Forward]
Fair value, beginning of period	$ 500,745	$ 596,378	$ 557,813	$ 580,860
Changes in valuation inputs or assumptions	(55,749)	22,578	(98,838)	59,252
Other changes, including realization of expected cash flows	(19,668)	(19,942)	(33,647)	(41,098)
Fair value, end of period	$ 425,328	$ 599,014	$ 425,328	$ 599,014