OTHER INCOME, NET - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Other Income and Expenses [Abstract]
Net unrealized mark-to-market gains on equity investments	$ 126,414	$ 8,000	$ 126,559	$ 10,600
Realized gains on equity investments	27,300		27,200
Net foreign currency exchange gains (losses)	10,000	(3,600)	2,100	(6,200)
Interest income	$ 7,000	2,500	$ 12,200	4,100
Realized gains (losses) on investments		21,200		21,300
Other-than-temporary impairment charge		$ 1,400		$ 4,800