DUE TO PRIME BROKERS AND OTHER FINANCIAL INSTITUTIONS (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Due to Prime Broker [Line Items]
Due to prime brokers and other financial institutions	$ 647,700	$ 319,830
Due to prime brokers and other financial institutions	$ 672,700	319,830
Greenlight Re
Due to Prime Broker [Line Items]
Maximum temporary leverage	30.00%
Maximum long-term leverage	15.00%
GRIL
Due to Prime Broker [Line Items]
Maximum temporary leverage	20.00%
Maximum long-term leverage	5.00%
Line of Credit [Member]
Due to Prime Broker [Line Items]
Other Short-term Borrowings	$ 25,000	$ 0

Due to Prime Broker [Line Items]

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- Definition

The maximum percentage of invested assets for which leverage is allowed over the long-term

+ References

No definition available.

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- Definition

Maximum percentage of assets that leverage is allowed on a temporary basis (30 days).

+ References

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- Definition

Amount of other payables due to broker-dealers or clearing organizations.

+ References

No definition available.

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- Definition

Amount of borrowings classified as other, maturing within one year or the normal operating cycle, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(a)(7))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

Amount payable to broker-dealers and clearing organizations, including, but not limited to, securities failed-to-receive, certain deposits received for securities loaned, open transactions, and floor-brokerage payables.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 940
-SubTopic 20
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=35710130&loc=d3e41645-110958

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