COMMON STOCK AND STOCK-BASED COMPENSATION PLANS (Tables)

6 Months Ended

Jun. 30, 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 six months ended June 30, 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		(12,911	)		15.90
Forfeited or expired		(1,461	)		18.82

Outstanding as of June 30, 2018 (2)		714,645		$	19.84		4.8	$	7,430

Exercisable as of June 30, 2018 (3)		569,977		$	18.74		4.2	$	6,552

(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 651,296 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 515,045 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 six months ended June 30, 2018, are as follows:


	Number of RSUs			Weighted Average Grant-Date Fair Value
Unvested as of December 31, 2017		560,616		$	29.31
Granted		255,500			35.77
Vested		(229,821	)		25.06
Forfeited or expired		(17,333	)		37.10

Unvested as of June 30, 2018		568,962		$	33.69

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:


	Six months ended June 30,				Three months ended June 30,
	2018 (unaudited)		2017 (unaudited)		2018 (unaudited)		2017 (unaudited)
Cost of revenue	$	325	$	205	$	168	$	114
Research and development, net		2,628		1,843		1,359		972
Sales and marketing		877		659		423		370
General and administrative		1,786		1,420		895		722

Total equity-based compensation expense	$	5,616	$	4,127	$	2,845	$	2,178

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:


	Six months ended June 30,
	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