NATURE OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Recent Accounting Pronouncements (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Equity investments without readily determinable fair value	$ 29,300		$ 32,300
Equity investments, fair value	18,600		12,200
Cumulative effect of adoption of new accounting standard			2,100
Net cash flows from (used in) investing activities	(20,950)	$ 158,159
Net cash flows from (used in) financing activities	$ (37,638)	332,409
Accounting Standards Update 2016-01 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of adoption of new accounting standard			$ 2,100
Accounting Standards Update 2016-15 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net cash flows from (used in) investing activities		3,000
Net cash flows from (used in) financing activities		$ 1,500