INVESTMENTS IN EXCESS MORTGAGE SERVICING RIGHTS ASSETS - Schedule of (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Servicing Assets at Fair Value [Line Items]
Mortgage servicing rights, at fair value	$ 5,021,086	$ 5,686,233
Excess MSRs And Excess Mortgage Servicing Rights Investees
Servicing Assets at Fair Value [Line Items]
Mortgage servicing rights, at fair value	458,923	505,343
Excess MSRs
Servicing Assets at Fair Value [Line Items]
Mortgage servicing rights, at fair value	346,450	379,747
Excess MSRs Investees
Servicing Assets at Fair Value [Line Items]
Mortgage servicing rights, at fair value	$ 112,473	$ 125,596

Fair value of an asset representing net future revenue from contractually specified servicing fees, late charges, and other ancillary revenues, in excess of future costs related to servicing arrangements.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 45
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6469459&loc=d3e122501-111745

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6469459&loc=d3e122492-111745

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=116651436&loc=d3e122625-111746

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 45
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6469459&loc=d3e122501-111745

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant