COMMON STOCK AND STOCKHOLDERS' EQUITY (Tables)

6 Months Ended

Jun. 30, 2017

Stockholders' Equity Note [Abstract]

Schedule of Restricted Stock Units And Restricted Stock Awards Activity

A summary of the activity for the Company’s RSUs and RSAs is presented below (in thousands, except share numbers, per share amounts, and contractual term):

	Number of Shares		Weighted- Average Grant Date Fair Value (per share)		Weighted- Average Remaining Contractual Term (Years)	Aggregate Intrinsic Value
Unvested balance – December 31, 2016	743,693		$	14.49	3.8	$	15,841
Granted	720,346		26.89
Vested	(187,783	)	13.70
Forfeited	(55,777	)	16.51
Unvested balance – June 30, 2017	1,220,479		$	21.83	3.4	$	33,197

Schedule of Stock Option Activity

A summary of the activity for the Company’s stock option plans during the reporting periods and a summary of information related to options vested and expected to vest and options exercisable are presented below (in thousands, except shares, per share amounts, contractual life):

	Options Outstanding
	Number of Shares Underlying Outstanding Options		Weighted- Average Exercise Price		Weighted-Average Grant Date Fair Value		Weighted- Average Remaining Contractual Life (Years)	Aggregate Intrinsic Value
Outstanding – December 31, 2016	3,843,276		$	10.93			7.5	$	39,902
Granted	549,759		25.68		$	11.12
Exercised	(411,076	)	11.03					6,648
Forfeited or cancelled	(112,249	)	15.25
Outstanding – June 30, 2017	3,869,710		$	12.89			7.3	$	55,445
Exercisable – June 30, 2017	2,091,253		$	8.78			6.2	$	38,511
Vested and expected to vest – June 30, 2017	3,818,858		$	12.80			7.3	$	55,038

Summary of Black-Scholes Option-Pricing Model to Determine Fair value of Stock Options

The following table summarizes the assumptions used in the Black-Scholes option-pricing model to determine the fair value of stock options granted:

	Six Months Ended June 30,
	2017	2016
Expected term (in years)	5.8	5.8
Expected volatility	42% - 44%	45%
Risk-free interest rate	1.9% - 2.0%	1.3% - 1.5%
Dividend yield	0%	0%

The following table summarizes the assumptions used in the Black-Scholes option-pricing model to determine fair value of our common shares to be issued under the ESPP:

	Six Months Ended June 30,
	2017	2016
Expected term (in years)	0.5 - 2.0	0.5 - 2.0
Expected volatility	35% - 50%	39% - 42%
Risk-free interest rate	0.45% - 1.22%	0.46% - 0.78%
Dividend yield	0.0%	0.0%

Summary of Stock-Based Compensation Expenses

Total stock-based compensation expense related to stock options, ESPP, RSUs and RSAs is included in the consolidated statements of operations as follows (in thousands):

	Three Months Ended June 30,				Six Months Ended June 30,
	2017		2016		2017		2016
Cost of revenue	$	366	$	220	$	627	$	435
Sales and marketing	671		440		1,177		1,023
Research and development	980		470		1,507		965
General and administrative	1,496		1,253		2,699		1,873
Total stock-based compensation expense	$	3,513	$	2,383	$	6,010	$	4,296