FAIR VALUE MEASUREMENTS AND FINANCIAL INSTRUMENTS - Realized and Unrealized Gains and Losses (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Equity Securities, FV-NI, Unrealized Gain (Loss) [Abstract]
Upward adjustments (gross unrealized gains)	$ 128,786		$ 128,786
Downward adjustments (including impairment) (gross unrealized losses)	(2,396)		(2,588)
Total	126,390		126,198
Equity Securities, FV-NI, Gain (Loss) [Abstract]
Realized gains, net, for equity securities sold	27,275		27,172
Unrealized gains, net, on equity securities held	126,414	$ 8,000	126,559	$ 10,600
Total gains recognized, net, in other income, net	$ 153,689		$ 153,731