FAIR VALUE MEASUREMENT (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Sep. 19, 2017	Jun. 14, 2017	Nov. 16, 2016
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at January 1	$ 23,100,000	$ 0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Total net (gains) losses included in earnings (realized and unrealized)	23,931,000	0
Additions	11,318,000	23,100,000
Payments	(1,000,000)	0
Balance at December 31	$ 57,349,000	$ 23,100,000
Minimum [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Contingent consideration on acquisition date			$ 0	$ 1,000,000.0	$ 22,500,000
Maximum [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Contingent consideration on acquisition date			$ 9,000,000	$ 8,000,000	$ 45,000,000