COMMON STOCK AND STOCK-BASED COMPENSATION PLANS (Tables)

3 Months Ended

Mar. 31, 2018

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

A summary of the Company’s stock option and SARs activities and related information for the three months ended March 31, 2018, are as follows:


	Number of options and SAR units (1)			Weighted average exercise price		Weighted average remaining contractual term		Aggregate intrinsic- value
Outstanding as of December 31, 2017		729,017		$	19.77		5.2	$	19,229
Granted		—			—
Exercised		(6,392	)		15.94
Forfeited or expired		(1,044	)		18.51

Outstanding as of March 31, 2018 (2)		721,581		$	19.81		5.0	$	11,828

Exercisable as of March 31, 2018 (3)		527,310		$	19.01		4.4	$	9,065

(1)	The SAR units are convertible for a maximum number of shares of the Company’s common stock equal to 75% of the SAR units subject to the grant.

(2)	Due to the ceiling imposed on the SAR grants, the outstanding amount equals a maximum of 656,498 shares of the Company’s common stock issuable upon exercise.

(3)	Due to the ceiling imposed on the SAR grants, the exercisable amount equals a maximum of 475,608 shares of the Company’s common stock issuable upon exercise.

Summary of Restricted Stock Units Activity

A summary of the Company’s RSU activities and related information for the three months ended March 31, 2018, are as follows:


	Number of RSUs			Weighted Average Grant-Date Fair Value
Unvested as of December 31, 2017		560,616		$	29.31
Granted		230,000			36.05
Vested		(153,503	)		25.92
Forfeited or expired		(4,001	)		34.10

Unvested as of March 31, 2018		633,112		$	32.55

Equity-Based Compensation Expense Included in Interim Condensed Consolidated Statements of Income

The following table shows the total equity-based compensation expense included in the interim condensed consolidated statements of income:


	Three months ended March 31,
	2018 (unaudited)		2017 (unaudited)
Cost of revenue	$	157	$	91
Research and development, net		1,269		871
Sales and marketing		454		289
General and administrative		891		698

Total equity-based compensation expense	$	2,771	$	1,949

Assumptions Used to Estimate Fair Value of Employee Stock Purchase Plan

The fair value for rights to purchase shares of common stock under the Company’s employee stock purchase plan was estimated on the date of grant using the following assumptions:


	Three months ended March 31,
	2018 (unaudited)		2017 (unaudited)
Expected dividend yield		0%		0%
Expected volatility		35%-42%		35%-46%
Risk-free interest rate		0.7%-1.6%		0.5%-0.7%
Contractual term of up to		24 months		24 months