FINANCIAL INSTRUMENTS Schedule of Reported Gains and Losses on Derivatives (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivatives recognized in income	$ 7,970	$ 4,136	$ (15,291)	$ 17,198
Commodity Swaps | Net investment income (loss)
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivatives recognized in income	1,794	(1,476)	(8,911)	(1,195)
Forwards | Net investment income (loss)
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivatives recognized in income	(28)	(116)	306	(184)
Futures | Net investment income (loss)
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivatives recognized in income	(77)	793	(480)	2,086
Interest Rate Swaps | Net investment income (loss)
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivatives recognized in income	113	0	20	0
Options, warrants, and rights | Net investment income (loss)
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivatives recognized in income	(6,467)	(2,834)	(18,579)	(5,082)
Total return swaps – equities | Net investment income (loss)
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivatives recognized in income	$ 12,635	$ 7,769	$ 12,353	$ 21,573