INVESTMENTS - Equity-method Investments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statements of Operations
Interest expense	$ (35,420)	$ (59,883)	$ (121,753)	$ (149,643)
Net realized and unrealized gain (loss) on investments			(320,388)	8,931
Net income (loss)	67,494	(20,898)	(187,847)	285,030
Equity Method Investment, Nonconsolidated Investee or Group of Investees
Statements of Operations
Revenues / investment income	268,389	353,289	1,057,398	1,584,552
Interest expense	(14,093)	(54,329)	(108,679)	(185,227)
Other expenses	(97,358)	(157,878)	(503,361)	(639,180)
Net realized and unrealized gain (loss) on investments	2,628,272	(204,820)	77,518	916,097
Net income (loss)	$ 2,785,210	$ (63,738)	$ 522,876	$ 1,676,242
Maximum
Schedule of Equity Method Investments [Line Items]
Ownership percentage	2.50%		2.50%