INVESTMENTS - Other Investments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Schedule of Investments [Line Items]
Realized gain (loss)	$ (19,635)	$ (3,664)	$ (97,642)	$ (9,036)
Net change in unrealized gain (loss)	533	(40,964)	(222,746)	17,967
Total gain (loss)			(320,388)	8,931
Other
Schedule of Investments [Line Items]
Realized gain (loss)	(1,479)	1,345	2,024	7,656
Net change in unrealized gain (loss)	(1,437)	17,472	(13,417)	12,018
Total gain (loss)	$ (2,916)	$ 18,817	$ (11,393)	$ 19,674