DUE TO PRIME BROKERS (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Due to Prime Brokers [Line Items]
Amounts due to prime brokers	$ 547,699	$ 319,830
GLRE
Due to Prime Brokers [Line Items]
Maximum temporary leverage	30.00%
Maximum long-term leverage	15.00%
GRIL
Due to Prime Brokers [Line Items]
Maximum temporary leverage	20.00%
Maximum long-term leverage	5.00%