SIGNIFICANT ACCOUNTING POLICIES (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Other-than-temporary impairment loss for marketable securities
Inventory write-offs included in cost of revenues	3,267	3,867	2,324
Provision for estimated sales returns, credits, stock rotations and other customer rights	$ 2,687	1,537
Warranty term	1 year
Governmental grants received	$ 937	712	545
Bank deposits, weighted-average duration of deposits	1 year 6 months
Bank deposits, weighted-average time to maturity	1 year 1 month 6 days
Bad debt expenses			109
Write-off of bad debts	154	100
Severance expenses	$ 4,066	$ 4,259	$ 3,296
Anti-dilutive shares excluded from computation of earnings per share amount	1,938,808	1,166,488	981,750
Amortization of deferred contract costs	$ 8,568	$ 6,821
Deferred commission costs capitalized	15,596	12,640
Deferred revenues recognized	$ 98,500	91,555
Period of remaining service of deferred revenue	3 years
Commissions expenses recognized	$ 3,199	5,121	$ 10,171
Remaining performance obligations	$ 234,982	$ 222,094
Percentage of remaining performance obligation that will be recognized as revenue over the next 12 months to total remaining performance obligation as of balance sheet date	56.00%
Expected period of benefit	3 years 3 months 18 days
S and P rating, A- or higher [Member]
Marketable securities, rating of investment portfolio percentage	94.00%
S and P rating, BBB or BBB+ [Member]
Marketable securities, rating of investment portfolio percentage	4.00%
S and P rating, BB- [Member]
Marketable securities, rating of investment portfolio percentage	2.00%
Israel [Member] \| S and P, A Rating [Member]
Percent of company's short-term and long-term bank deposits held in major Israeli banks	25.00%
Israel [Member] \| S and P, AAA Rating [Member]
Percent of company's short-term and long-term bank deposits held in major Israeli banks	32.00%
Israel [Member] \| S and P, BBB+ Rating [Member]
Percent of company's short-term and long-term bank deposits held in major Israeli banks	7.00%
The United States [Member] \| Debt Securities [Member]
Marketable securities, percentage of portfolio distribution	45.00%
The United States [Member] \| S and P, A Rating [Member]
Percent of company's short-term and long-term bank deposits held in major Israeli banks	36.00%
Europe [Member] \| Debt Securities [Member]
Marketable securities, percentage of portfolio distribution	29.00%
Other [Member] \| Debt Securities [Member]
Marketable securities, percentage of portfolio distribution	26.00%
Minimum [Member]
Finite-lived intangible assets, estimated useful lives	5 years
Customer support contracts, support period	1 year
Maximum [Member]
Finite-lived intangible assets, estimated useful lives	9 years
Customer support contracts, support period	3 years
Bank deposits, maximum contractual term	2 years

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Governmental grants received upon compliance with certain applicable requirements and conditions specified in the Chief Scientist''s program and with the provisions of the Law for the Encouragement of Research and Development in the Industry, 1984. These grants are deducted from research and development expenses.

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Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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