SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES, Part 2 (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash and Cash Equivalents [Abstract]
Maximum maturity period for classification of cash equivalents	3 months
Restricted Cash [Abstract]
Restricted cash in long-term assets	$ 11,600	$ 32,802
Advertising Costs [Abstract]
Advertising expense	$ 29,400	$ 27,000	$ 28,000
Goodwill and Other Intangible Assets [Abstract]
Impairment of goodwill			$ 9,900