Note A - Basis of Presentation and Summary of Significant Accounting Policies - Impact of New Standard on Consolidated Balance Sheet and Consolidated Statements of Operations (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Income statement
Revenues		$ 32,619	$ 34,277	$ 91,381	$ 93,511
Cost of revenues	[1]	16,315	18,270	46,311	50,760
Gross margin:		16,304	16,007	45,070	42,751
Research and development, net	[2]	9,614	9,214	27,503	27,565
Sales and marketing	[3]	3,640	3,635	11,468	10,640
General and administrative	[4]	2,362	2,483	7,612	7,342
Amortization of intangible assets		425	425	1,276	1,275
Total operating expenses:		16,041	15,757	47,859	46,822
Operating loss:		263	250	(2,789)	(4,071)
Financial income, net		492	382	1,291	1,216
Loss before taxes on income		755	632	(1,498)	(2,855)
Taxes on income		350	54	139	19
Net income (loss)		405	$ 578	(1,637)	$ (2,874)
Assets
Trade receivables		21,448		21,448		$ 13,416
Inventories		8,247		8,247		9,422
Other accounts receivable and prepaid expenses		2,843		2,843		3,167
Liabilities
Accrued expenses and other accounts payable		(3,783)		(3,783)		(2,888)
Equity
Accumulated deficit		(110,873)		(110,873)		$ (104,842)
Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Income statement
Revenues		31,553		89,335
Cost of revenues		15,934		45,553
Gross margin:		15,619		43,782
Research and development, net		9,614		27,503
Sales and marketing		3,579		11,357
General and administrative		2,362		7,612
Amortization of intangible assets		425		1,276
Total operating expenses:		15,980		47,748
Operating loss:		(361)		(3,966)
Financial income, net		492		1,291
Loss before taxes on income		131		(2,675)
Taxes on income		350		139
Net income (loss)		(219)		(2,814)
Assets
Trade receivables		19,285		19,285
Inventories		9,023		9,023
Other accounts receivable and prepaid expenses		2,959		2,959
Liabilities
Accrued expenses and other accounts payable		(3,783)		(3,783)
Equity
Accumulated deficit		(112,143)		(112,143)
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Accounting Standards Update 2014-09 [Member]
Income statement
Revenues		1,066		2,046
Cost of revenues		382		758
Gross margin:		684		1,288
Research and development, net
Sales and marketing		60		111
General and administrative
Amortization of intangible assets
Total operating expenses:		60		111
Operating loss:		624		1,177
Financial income, net
Loss before taxes on income		624		1,177
Taxes on income
Net income (loss)		624		1,177
Assets
Trade receivables		2,163		2,163
Inventories		(776)		(776)
Other accounts receivable and prepaid expenses		(116)		(116)
Liabilities
Accrued expenses and other accounts payable
Equity
Accumulated deficit		$ 1,271		$ 1,271

[1] Includes equity-based compensation expense in the amount of $114 and $84 for the three months ended September 30, 2018 and 2017, and $320 and $275 for the nine months ended September 30, 2018 and 2017, respectively.

[2] Includes equity-based compensation expense in the amount of $781 and $576 for the three months ended September 30, 2018 and 2017, respectively; and $2,134 and $1,815 for the nine months ended September 30, 2018 and 2017, respectively.

[3] Includes equity-based compensation expense in the amount of $283 and $273 for the three months ended September 30, 2018 and 2017, respectively; and $954 and $870 for the nine months ended September 30, 2018 and 2017, respectively.

[4] Includes equity-based compensation expense in the amount of $574 and $505 for the three months ended September 30, 2018 and 2017, respectively; and $1,703 and $1,566 for the nine months ended September 30, 2018 and 2017, respectively.