REAL ESTATE SECURITIES - Additional Information (Details) - USD ($)	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Investments, Debt and Equity Securities [Abstract]
Unrealized gain (loss) on equity securities	$ 0	$ 72,000.0	$ 86,900	$ 72,000
Other than temporary impairment losses included in consolidated statements of income	$ 0	$ 600,000	$ 0	$ 1,600,000

Amount of realized gain (loss) from sale of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 321
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=116654751&loc=SL75117546-209714

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration