SHAREHOLDERS' EQUITY (Tables)

12 Months Ended

Dec. 31, 2018

Stockholders' Equity Note [Abstract]

Composition of Shares Capital

Composition of shares capital of the Company:

December 31, 2017		December 31, 2018
Authorized	Issued and outstanding	Authorized	Issued and outstanding
Number of shares
500,000,000	46,453,583	500,000,000	49,269,626

Total Share-Based Compensation Expense

The total share-based compensation expense related to all of the Company's equity-based awards, which include options, RSUs and employee stock purchase rights issued pursuant to our Employee Share Purchase Plan (“ESPP”) and recognized for the years ended December 31, 2016, 2017 and 2018 was comprised as follows:

	Year ended December 31,
	2016		2017		2018
Cost of revenues	$	1,798	$	2,930	$	4,418
Research and development		14,543		26,227		39,417
Sales and marketing		4,553		6,585		9,770
General and administrative		7,154		11,958		18,725
Total share-based compensation expense	$	28,048	$	47,700	$	72,330

Schedule of Stock Options Granted to Employees Activity

A summary of the activity in options granted to employees for the year ended December 31, 2018 is as follows:

	Number of options			Weighted average exercise price		Weighted average remaining contractual term (in years)		Aggregate intrinsic value
Balance as of December 31, 2017		8,198,154		$	16.65		6.27	$	337,517
Granted		1,258,302		$	68.25
Exercised		(1,761,534	)	$	13.29
Forfeited		(31,609	)	$	38.79
Balance as of December 31, 2018		7,663,313		$	25.81		5.91	$	496,978
Exercisable as of December 31, 2018		5,110,726		$	14.2		4.83	$	389,208
Vested and expected to vest as of December 31, 2018		7,536,284		$	25.3		5.87	$	492,396

Schedule of Stock Option Valuation Assumptions - Compensation to Employees

The following table set forth the parameters used in computation of the options compensation to employees for the years ended December 31, 2016, 2017 and 2018:

	Year ended December 31,
	2016		2017		2018
Expected volatility		49.6%-54.0%		45.46%-48.04		45.19%-46.64%
Expected dividends		0%		0%		0%
Expected term (in years)		5 -6.32		5.03 -7.07		5.17 -7.53
Risk free rate		1.15%-2.26%		1.82%-2.27%		2.59%-3.03%

Summary of Options Data

A summary of options data for the years ended December 31, 2016, 2017 and 2018, is as follows:

	Year ended December 31,
	2016		2017		2018
Weighted-average grant date fair value  of options granted	$	9.02	$	27.50	$	34.93
Total intrinsic value of the options exercised	$	64,062	$	75,763	$	137,448
Total fair value of shares vested	$	18,602	$	20,780	$	27,629

Schedule of Options Outstanding and Exercisable

The following tables summarize information about the Company's outstanding and exercisable options granted to employees as of December 31, 2018:

Exercise price (Range)		Options outstanding as of December 31, 2018		Weighted average remaining contractual term		Options exercisable as of December 31, 2018		Weighted average remaining contractual term
				(years)				(years)
	0.001-0.08		1,217,241		4.64		947,832		4.61
	0.09-0.5		1,285,879		1.97		1,285,879		1.97
	0.51-8.73		744,092		4.01		744,092		4.01
	8.74-19.86		672,158		5.86		589,790		5.82
	19.87-21.13		814,247		6.75		563,773		6.63
	21.14-51.32		707,035		7.20		414,664		6.82
	51.33-52.2		739,000		8.12		323,310		8.12
	52.21-60.33		264,532		9.05		51,741		9.01
	60.34-61.75		719,000		9.12		75,748		9.12
	61.76-108.9		500,129		9.23		113,897		8.80
			7,663,313		5.91		5,110,726		4.83

Schedule Stock Options Outstanding and Exercisable to Non-Employees

The following table summarizes information about the Company's outstanding and exercisable options to purchase ordinary shares granted to non-employees consultants as of December 31, 2018:

	Options
	outstanding				Exercisable
	as of				as of
Grant	December 31,		Exercise		December 31,		Exercisable
date	2018		price		2018		Through
January 25, 2011		10,000		0.67		10,000	January 25, 2021
January 9, 2013		3,400		2.34		3,400	January 9, 2023
		13,400				13,400

Schedule of Stock Option Valuation Assumptions - Non-Employees

The following table set forth the parameters used in computation of the employee stock purchase plan for the years ended December 31, 2016, 2017 and 2018:

	Year ended December 31,
	2016		2017		2018
Expected volatility		44.6%-45.8%		33.6%-43.4%		39.9%-41.2%
Expected dividends		0%		0%		0%
Expected term (in years)		0.5		0.5		0.5
Risk free rate		0.26%-0.46%		0.47%-0.79%		1.85%-2.28%

Schedule of Restricted Stock Unit Activity

A summary of RSU activity for the year ended December 31, 2018, is as follows:

	Number of shares			Weighted average grant date fair value Per Share
Unvested as of December 31, 2017		2,080,126		$	48.62
Granted		1,052,893		$	84.04
Vested		(870,733	)	$	46.72
Forfeited		(171,774	)	$	57.79
Unvested as of December 31, 2018		2,090,512		$	66.53