BUSINESS COMBINATIONS - Pro forma summary of financials (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Business Acquisition, Pro Forma Information [Abstract]
Net revenues	$ 329,443	$ 269,494	$ 875,108	$ 743,328
Net income (loss)	$ (4,888)	$ (19,221)	$ (25,502)	$ (85,210)
Net income (loss) per common share - basic (in dollars per share)	$ (0.04)	$ (0.14)	$ (0.19)	$ (0.63)
Net income (loss) per common share - diluted (in dollars per share)	$ (0.04)	$ (0.14)	$ (0.19)	$ (0.63)
Weighted shares outstanding basic (in shares)	135,893,823	134,735,075	135,857,127	134,753,276
Weighted shares outstanding diluted (in shares)	135,893,823	134,735,075	135,857,127	134,753,276