Note 2 - Significant Accounting Policies - Impact of New Standard on Consolidated Balance Sheet and Consolidated Statements of Operations (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues		$ 117,438	$ 124,753	$ 137,869
Cost of revenues	[1]	59,991	67,058	77,023
Gross margin:		57,447	57,695	60,846
Research and development	[2]	36,109	36,655	34,885
Sales and marketing	[3]	15,323	14,315	13,867
General and administrative	[4]	9,955	9,789	9,006
Amortization of intangible assets		1,700	1,700	1,457
Total operating expenses:		63,087	62,459	56,666
Operating loss:		(5,640)	(4,764)	4,180
Losses on available-for-sale marketable securities		1,815	1,669	1,227
Loss before taxes on income		(3,825)
Taxes on income		1,868	92	(594)
Net income (loss)		(1,957)	(3,003)	4,813
Trade receivables		13,475	13,416
Inventories (Note 5)		9,819	9,422	$ 9,748
Other accounts receivable and prepaid expenses (Note 4)		3,670	3,167
Accrued expenses and other accounts payable		(3,461)	(2,888)
Accumulated deficit		(112,363)	$ (104,842)
Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Revenues		117,127
Cost of revenues		59,884
Gross margin:		57,243
Research and development		36,109
Sales and marketing		15,307
General and administrative		9,955
Amortization of intangible assets		1,700
Total operating expenses:		63,071
Operating loss:		(5,828)
Losses on available-for-sale marketable securities		1,815
Loss before taxes on income		(4,013)
Taxes on income		1,868
Net income (loss)		(2,145)
Trade receivables		13,048
Inventories (Note 5)		9,943
Other accounts receivable and prepaid expenses (Note 4)		3,691
Accrued expenses and other accounts payable		(3,461)
Accumulated deficit		(112,645)
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Accounting Standards Update 2014-09 [Member]
Revenues		311
Cost of revenues		107
Gross margin:		204
Research and development
Sales and marketing		16
General and administrative
Amortization of intangible assets
Total operating expenses:		16
Operating loss:		188
Losses on available-for-sale marketable securities
Loss before taxes on income		188
Taxes on income
Net income (loss)		188
Trade receivables		427
Inventories (Note 5)		(124)
Other accounts receivable and prepaid expenses (Note 4)		(21)
Accrued expenses and other accounts payable
Accumulated deficit		$ 282

[1] Includes equity-based compensation expense in the amount of $428, $352 and $328 for the years ended December 31, 2018, 2017 and 2016, respectively.

[2] Includes equity-based compensation expense in the amount of $2,873, $2,349 and $2,205 for the years ended December 31, 2018, 2017 and 2016, respectively.

[3] Includes equity-based compensation expense in the amount of $1,248, $1,115 and $806 for the years ended December 31, 2018, 2017 and 2016, respectively.

[4] Includes equity-based compensation expense in the amount of $2,255, $2,045 and $1,749 for the years ended December 31, 2018, 2017 and 2016, respectively.