STOCK-BASED COMPENSATION - Expense (Details) - USD ($) $ in Thousands, shares in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Employee Stock Purchase Plan 2016 [Member]
Discount from market price (as a percent)	15.00%
Allocated share-based compensation expense	$ 32	$ 29
Stock-based compensation shares available	0.2
Stock Incentive Plan 2008 [Member]
Allocated share-based compensation expense	$ 1,837	2,395
Stock-based compensation shares available	0.6
Cost of sales [Member] | Employee Stock Purchase Plan 2016 [Member]
Allocated share-based compensation expense	$ 4	4
Cost of sales [Member] | Stock Incentive Plan 2008 [Member]
Allocated share-based compensation expense		26
Research and development Expense [Member] | Employee Stock Purchase Plan 2016 [Member]
Allocated share-based compensation expense	5	7
Research and development Expense [Member] | Stock Incentive Plan 2008 [Member]
Allocated share-based compensation expense	114	187
Selling, general and administrative Expenses [Member] | Employee Stock Purchase Plan 2016 [Member]
Allocated share-based compensation expense	23	18
Selling, general and administrative Expenses [Member] | Stock Incentive Plan 2008 [Member]
Allocated share-based compensation expense	$ 1,723	$ 2,182