STOCK-BASED COMPENSATION - Employee Stock Purchase Plan - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jun. 25, 2009
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Proceeds from common stock issued	$ 1,090,000	$ 944,000	$ 566,000
Employee Stock Purchase Plan (ESPP) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Reserved for issuance (in shares)				1,000,000
Purchase period (in months)	3 months
Percentage of market value (in hundredths)	85.00%
Maximum allocation of base compensation (in hundredths)	10.00%
Maximum shares per purchase date (in shares)	12,500
Maximum value per calendar year, per employee	$ 25,000
Common stock issued (in shares)	10,303	9,730	9,386
Proceeds from common stock issued	$ 798,000	$ 734,000	$ 439,000
Employee Stock Purchase Plan (ESPP) [Member] | Selling, General and Administrative Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Charges to expense	82,000	69,000	45,000
Employee Stock Purchase Plan (ESPP) [Member] | Manufacturing Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Charges to expense	81,000	46,000	15,000
Employee Stock Purchase Plan (ESPP) [Member] | Research and Development Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Charges to expense	$ 130,000	$ 94,000	$ 67,000