SEGMENT AND GEOGRAPHICAL INFORMATION - Long-lived Assets by Geographic Area (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 934,586	$ 597,766
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	918,351	586,702
International
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 16,235	$ 11,064