STOCK-BASED COMPENSATION - Schedule of Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Stock-based compensation
Total	$ 10,924	$ 10,596
Cost of sales (excluding amortization of intangible assets)
Stock-based compensation
Total	92	106
Research and development expenses
Stock-based compensation
Total	268	693
Selling, general and administrative expenses
Stock-based compensation
Total	9,565	9,797
Restructuring charges
Stock-based compensation
Total	$ 999	$ 0