MORTGAGE LOAN RECEIVABLES - Provision for Loan Losses (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Allowance for Loan and Lease Losses [Roll Forward]
Provision for loan losses at beginning of period	$ 4,000	$ 3,700	$ 3,100
Provision for loan losses	0	300	600
Provision for loan losses at end of period	$ 4,000	$ 4,000	$ 3,700

Amount of increase (decrease) of allowance reserve for credit loss.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.7(d))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

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- Definition

The reserve to cover probable credit losses related to specifically identified fixed maturity real estate loans as well as probable credit losses inherent in the remainder of that loan portfolio.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 310
-Section 45
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=82921503&loc=d3e21338-158488

+ Details

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Balance Type:	credit
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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

+ Details

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