FAIR VALUE OF FINANCIAL INSTRUMENTS - Recurring and Nonrecurring Fair value Measurements Within Hierarchy (Details) - Recurring $ in Thousands	Jun. 30, 2020 USD ($)
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Financial assets by level within fair value hierarchy	$ 184,559
Level 1 | Short-term investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Financial assets by level within fair value hierarchy	56,536
Level 1 | Cash and cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Financial assets by level within fair value hierarchy	128,023
Carrying Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Financial assets by level within fair value hierarchy	184,559
Carrying Value | Short-term investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Financial assets by level within fair value hierarchy	56,536
Carrying Value | Cash and cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Financial assets by level within fair value hierarchy	128,023
Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Financial assets by level within fair value hierarchy	184,559
Fair Value | Short-term investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Financial assets by level within fair value hierarchy	56,536
Fair Value | Cash and cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Financial assets by level within fair value hierarchy	$ 128,023