FAIR VALUE MEASUREMENTS AND FAIR VALUE OF FINANCIAL INSTRUMENTS - Additional information (Details)	3 Months Ended
	Mar. 31, 2020 USD ($) position	Mar. 31, 2019 USD ($)	Dec. 31, 2019 position
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment interest income	$ 1,700,000	$ 1,600,000
Debt securities, available-for-sale, allowance for credit loss	$ 0
Debt instruments held in continuous unrealized loss position | position	33		18
Discount rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability, measurement input	0.168
Discount rate | Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability, measurement input	0.168
Probability of the occurrence of certain events
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability, measurement input	0.200
Probability of the occurrence of certain events | Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability, measurement input	0.200
Term Loan | Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt instrument, fair value	$ 52,700,000