v3.20.1

FAIR VALUE OF FINANCIAL INSTRUMENTS - Investments Valued Under the Measurement Alternative (Details) - USD ($) $ in Thousands | 3 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Mar. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Equity Securities without Readily Determinable Fair Value [Roll Forward] |  |  |
Beginning balance, before cumulative impairment |  | $ 3,305 | $ 11,205
Accumulated impairment as of January 1, |  | 0 | $ 0
Beginning balance, after cumulative impairment | $ 3,305 | 11,205 |
Removal of investment in connection with step acquisition | 0 | (9,700) |
Acquisition of interest in a privately held company | 0 | 1,800 |
Ending period balance | $ 3,305 | $ 3,305 |

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