INVESTMENTS - Other Investments (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Schedule of Investments [Line Items]
Realized gain	$ (39,247)	$ (5,819)
Net change in unrealized gain (loss)	(326,067)	57,117
Total gain (loss)	(365,314)	51,298
Other Investments at Fair Value
Schedule of Investments [Line Items]
Realized gain	87	0
Net change in unrealized gain (loss)	(4,254)	5,719
Total gain (loss)	$ (4,167)	$ 5,719