SEGMENT INFORMATION, GEOGRAPHIC INFORMATION AND CUSTOMER CONCENTRATION - Reconciliation of Segment Operating Income to Consolidated Income Before Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total segment operating income	$ 18,809	$ (12,449)	$ 13,083
Unallocated corporate expenses	(240,933)	(207,446)	(209,929)
Stock-based compensation	(24,056)	(18,040)	(12,074)
Loss on convertible debt extinguishment	0	(1,362)	(5,695)
Non-operating expense, net	(9,938)	(12,406)	(13,984)
Income (loss) before income taxes	8,871	(26,217)	(6,596)
Operating Segments
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total segment operating income	44,059	12,977	38,008
Corporate, Non-Segment
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Unallocated corporate expenses	(681)	(3,416)	(4,532)
Stock-based compensation	(24,062)	(18,040)	(12,074)
Amortization of intangibles	$ (507)	$ (3,970)	$ (8,319)