INVESTMENTS IN RESIDENTIAL MORTGAGE LOANS - Schedule of Real Estate Owned (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Real Estate Owned [Roll Forward]
Beginning balance	$ 59,591	$ 50,574
Purchases	38,127	11,283
Transfer of loans to real estate owned	124,013	81,940
Sales	(95,456)	(66,880)
Valuation provision on REO	2,020	(17,326)
Ending balance	$ 128,295	$ 59,591

Value transferred from mortgage loans to real estate owned (REO) in noncash transactions.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4332-108586

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4304-108586

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4313-108586

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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