Significant Accounting Policies (Details Textual) - USD ($)		12 Months Ended
	Aug. 21, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	May 11, 2020
Significant Accounting Policies [Line Items]
Operating lease, impairment loss		$ 3,149,000	$ 0	$ 0
Contract with customer, liability, revenue recognized		96,535,000
Sales returns		$ 0	0	0
Capitalized contract cost, amortization period (years)		4 years
Granted (in shares)		10,933
Stock-based compensation		$ 68,585,000	46,139,000	34,961,000
Gain (loss) on derivative instruments reclassified into earnings, net of tax		257,000	352,000	(3,741,000)
Realized income on derivative instruments, net of tax		6,052,000	0	0
Derivative instruments not designated as hedging instruments, gain (loss), net		(1,144,000)	683,000
Severance and retirement costs		$ 7,169,000	$ 6,390,000	$ 6,765,000
Restricted Stock Units and Stock Options
Significant Accounting Policies [Line Items]
Antidilutive securities excluded from computation of earnings per share, shares		3,148,442	3,033,718
Credit and Security Agreement | London Interbank Offered Rate (LIBOR)
Significant Accounting Policies [Line Items]
Basis spread on variable rate	3.00%
Credit and Security Agreement | Base Rate
Significant Accounting Policies [Line Items]
Basis spread on variable rate	0.50%
2025 Senior Notes
Significant Accounting Policies [Line Items]
Debt instrument, face amount		$ 253,000,000
2025 Senior Notes | Convertible Debt Securities
Significant Accounting Policies [Line Items]
Antidilutive securities excluded from computation of earnings per share, shares		2,746,418
Line of Credit | Revolving Credit Facility
Significant Accounting Policies [Line Items]
Debt instrument, term	3 years
Maximum borrowing capacity	$ 70,000,000
Line of credit facility, accordion feature, increase limit	$ 90,000,000
First priority perfected lien on voting capital stock, percent	65.00%
Debt instrument, covenant, minimum available liquidity	$ 25,000,000
Line of Credit | Letter of Credit
Significant Accounting Policies [Line Items]
Maximum borrowing capacity	$ 15,000,000
Convertible Debt | 2025 Senior Notes
Significant Accounting Policies [Line Items]
Interest rate, stated percentage					1.25%
Initial conversion price (in dollars per share)		$ 92.12
Debt instrument, face amount					$ 253,000,000
Other Noncurrent Liabilities
Significant Accounting Policies [Line Items]
Restructuring reserve		$ 2,727,000	$ 2,554,000
Israel | VSUK Plan
Significant Accounting Policies [Line Items]
Defined contribution plan, maximum annual contributions per employee, percent		8.33%
Israel | VSIR Plan
Significant Accounting Policies [Line Items]
Defined contribution plan, employer matching contribution, percent of match		100.00%
United Kingdom | VSUK Plan
Significant Accounting Policies [Line Items]
Defined contribution plan, employer matching contribution, percent of match		100.00%
Defined contribution plan, employer matching contribution, percent of base pay		3.00%
Australia | VAUS Plan
Significant Accounting Policies [Line Items]
Defined contribution plan, employer matching contribution, percent of employees' eligible wages		9.50%
Deferred Salary Arrangement | United States
Significant Accounting Policies [Line Items]
Defined contribution plan, employer matching contribution, percent of match		100.00%
Defined contribution plan, employer matching contribution, percent of participants contribution		50.00%
Foreign Exchange Contract
Significant Accounting Policies [Line Items]
Gain (loss) on derivative instruments reclassified into earnings, net of tax		$ 257,000	$ 352,000
Realized income on derivative instruments, net of tax		$ 6,052,000
United States of America, Dollars
Significant Accounting Policies [Line Items]
Investment interest rate			1.71%
Minimum | Credit and Security Agreement | London Interbank Offered Rate (LIBOR)
Significant Accounting Policies [Line Items]
Basis spread on variable rate	1.00%
Minimum | Israel | VSIR Plan
Significant Accounting Policies [Line Items]
Defined contribution plan, employer matching contribution, percent of base pay		3.00%
Defined contribution plan, employer matching contribution, percent of participants contribution		3.00%
Minimum | Deferred Salary Arrangement | United States
Significant Accounting Policies [Line Items]
Defined contribution plan, contributions, percentage of participants base pay		3.00%
Minimum | United States of America, Dollars
Significant Accounting Policies [Line Items]
Investment interest rate		0.10%
Maximum | Israel | VSIR Plan
Significant Accounting Policies [Line Items]
Defined contribution plan, employer matching contribution, percent of base pay		5.00%
Defined contribution plan, employer matching contribution, percent of participants contribution		50.00%
Maximum | Netherlands | VNL Plan
Significant Accounting Policies [Line Items]
Defined contribution plan, employer matching contribution, percent of base pay		7.70%
Maximum | Deferred Salary Arrangement | United States
Significant Accounting Policies [Line Items]
Defined contribution plan, employer matching contribution, percent of base pay		3.00%
Defined contribution plan, contributions, percentage of participants base pay		5.00%
Participant matching contribution percentage of base remuneration		80.00%
Maximum | United States of America, Dollars
Significant Accounting Policies [Line Items]
Investment interest rate		0.16%
Maintenance and services
Significant Accounting Policies [Line Items]
Revenue, performance obligation, description of timing		one year