STOCK-BASED COMPENSATION - Stock-based compensation expense (Details) - USD ($) $ in Thousands, shares in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Employee Stock Purchase Plan 2016 [Member]
Stock-based compensation shares available	0.2		0.2
Discount from market price (as a percent)			15.00%
Allocated Share-based Compensation Expense	$ 57	$ 30	$ 86	$ 60
Stock Incentive Plan 2008 [Member]
Stock-based compensation shares available	1.1		1.1
Allocated Share-based Compensation Expense	$ 5,679	2,563	$ 8,074	4,243
Cost of sales [Member] | Employee Stock Purchase Plan 2016 [Member]
Allocated Share-based Compensation Expense	7	3	11	6
Cost of sales [Member] | Stock Incentive Plan 2008 [Member]
Allocated Share-based Compensation Expense	33	28	59	49
Research and development Expense [Member] | Employee Stock Purchase Plan 2016 [Member]
Allocated Share-based Compensation Expense	12	4	19	9
Research and development Expense [Member] | Stock Incentive Plan 2008 [Member]
Allocated Share-based Compensation Expense	146	219	333	332
Selling, general and administrative Expenses [Member] | Employee Stock Purchase Plan 2016 [Member]
Allocated Share-based Compensation Expense	38	23	56	45
Selling, general and administrative Expenses [Member] | Stock Incentive Plan 2008 [Member]
Allocated Share-based Compensation Expense	$ 5,500	$ 2,316	$ 7,682	$ 3,862