FINANCIAL INSTRUMENTS - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Assets:
Cash equivalents		$ 180,865
Quoted Market Prices in Active Markets for Identical Assets (Level 1)
Assets:
Cash equivalents		150,865
Significant Other Observable Inputs (Level 2)
Assets:
Cash equivalents		30,000
Money market funds
Assets:
Cash equivalents	$ 2,277	150,865
Money market funds | Quoted Market Prices in Active Markets for Identical Assets (Level 1)
Assets:
Cash equivalents	2,277	150,865
Money market funds | Significant Other Observable Inputs (Level 2)
Assets:
Cash equivalents	$ 0	0
Time deposits
Assets:
Cash equivalents		30,000
Time deposits | Quoted Market Prices in Active Markets for Identical Assets (Level 1)
Assets:
Cash equivalents		0
Time deposits | Significant Other Observable Inputs (Level 2)
Assets:
Cash equivalents		$ 30,000