SEGMENT AND GEOGRAPHIC DISCLOSURES - Geographic Breakdown of Revenues (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Revenues from External Customers [Line Items]
Revenues	$ 194,618	$ 236,839
United States
Revenues from External Customers [Line Items]
Revenues	141,832	173,510
Canada
Revenues from External Customers [Line Items]
Revenues	16,494	21,209
Europe
Revenues from External Customers [Line Items]
Revenues	25,711	28,546
Other foreign countries
Revenues from External Customers [Line Items]
Revenues	$ 10,581	$ 13,574