FAIR VALUE MEASUREMENTS - Additional information (Details) - USD ($)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Oct. 31, 2018	Jun. 11, 2018	Jun. 14, 2017	May 31, 2017
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Annual interest rate on convertible senior notes						0.625%
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 33,464,000	$ 38,837,000
Change in fair value of contingent consideration	(8,122,000)	14,592,000
Contingent consideration additions	0	0
Contingent consideration payments	(3,000,000)	(4,000,000)
Ending balance	22,342,000	49,429,000
Minimum
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Contingent consideration			$ 0	$ 0	$ 0
Maximum
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Contingent consideration			$ 46,800,000	$ 4,400,000	$ 1,000,000.0
SnapCap
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Business Combination, Contingent Consideration, Future Known Payment	3,000,000.0
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Change in fair value of contingent consideration	$ (1,000)	$ 1,592,000