SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Narrative) (Details)	12 Months Ended
Dec. 31, 2017 USD ($) financial_institution	Dec. 31, 2016 USD ($)
Debt Instrument [Line Items]
Investment held-to-maturity	$ 0	$ 4,747,000
Deferred Revenue, Revenue Recognized	$ 653,000	302,000
Number of financial institutions \| financial_institution	1
Held-to-maturity Securities [Abstract]
Unrecognized holding loss		2,000
Fair value of debt securities		4,700,000
Investment income	$ 67,000	22,000
Income Taxes
Unrecognized tax benefits	0	0
Income tax penalties and interest expense	$ 0	0
Minimum
Property and Equipment
Useful lives	3 years
Maximum
Property and Equipment
Useful lives	5 years
Commercial Paper
Debt Instrument [Line Items]
Investment held-to-maturity		4,000,000
Commercial Paper \| Commercial Paper, Maturing January 2017
Debt Instrument [Line Items]
Investment held-to-maturity		3,000,000
Commercial Paper \| Commercial Paper, Maturing February 2017
Debt Instrument [Line Items]
Investment held-to-maturity		1,000,000
Debt Securities \| Certificates of Deposit
Debt Instrument [Line Items]
Investment held-to-maturity		747,000
Debt Securities \| Certificates of Deposit \| Certificate of Deposit, Maturing January 2017
Held-to-maturity Securities [Abstract]
Fair value of debt securities	$ 200,000	$ 249,000
Debt Securities \| Certificates of Deposit \| Certificate of Deposit, Maturing February 2017
Held-to-maturity Securities [Abstract]
Fair value of debt securities	200,000
Debt Securities \| Certificates of Deposit \| Certificate of Deposit, Maturing March 2017
Held-to-maturity Securities [Abstract]
Fair value of debt securities	200,000
Development of Filter Designs
Held-to-maturity Securities [Abstract]
Deferred revenue	$ 143,000

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