COMMON STOCK AND STOCKHOLDERS' EQUITY (Tables)

9 Months Ended

Sep. 30, 2016

Stockholders' Equity Note [Abstract]

Schedule of Redeemable Convertible Preferred Stock into Common Stock

As a result of this amendment, the redeemable convertible preferred stock became convertible into shares of common stock upon a qualifying event, including completion of an initial public offering, as follows:

Preferred Stock	Number of Shares, Actual	Conversion Rate	Number of Shares, As Converted
Series A	1,319,940	1.0088	1,331,507
Series B	988,411	1.0148	1,003,071
Series C	4,019,524	1.0192	4,096,561
Series D	5,308,875	1.0218	5,424,802
Series E	2,439,058	1.0000	2,439,058
Series F	2,685,997	1.0000	2,685,997
Series G	3,692,684	1.0000	3,692,684
Total	20,454,489		20,673,680

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 life years):

	Number of Shares		Weighted- Average Grant Date Fair Value (per share)		Weighted- Average Remaining Contractual Life (Years)	Aggregate Intrinsic Value
Unvested balance – December 31, 2015	—		$	—		$	—
Granted	937,863		13.74
Vested	(207,860	)	12.92
Forfeited	(11,850	)	13.84
Unvested balance – September 30, 2016	718,153		$	13.97	3.8	$	14,119
Expected to vest – September 30, 2016	679,139		$	13.97	3.8	$	13,352

Schedule of Stock Option Activity

The following table summarizes the Company’s stock option activity for the nine months ended September 30, 2016 (in thousands, except share numbers, per share amounts, and contractual life years):

	Options Outstanding
	Number of Shares Underlying Outstanding Options		Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Life (Years)	Aggregate Intrinsic Value
Outstanding – December 31, 2015	4,311,463		$	9.87	7.9	$	22,709
Granted	612,144		13.89		9.4
Exercised	(679,175	)	7.45		—
Forfeited or cancelled	(187,185	)	12.68		—
Outstanding – September 30, 2016	4,057,247		$	10.75	7.9	$	36,161
Exercisable – September 30, 2016	2,089,327		$	7.93	6.6	$	24,514
Vested and expected to vest – September 30, 2016	3,988,909		$	10.70	7.6	$	35,755

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 the Company’s stock options:

	Nine Months Ended September 30,
	2016	2015
Expected term (in years)	5.8	5.8
Expected volatility	44% - 45%	45% - 46%
Risk-free interest rate	1.2% - 1.5%	1.4% - 1.8%
Dividend yield	0%	0%

Summary of Stock-Based Compensation Expenses

Total stock-based compensation expense was allocated as follows (in thousands):

	Three Months Ended September 30,				Nine Months Ended September 30,
	2016		2015		2016		2015
Cost of revenue	$	231	$	219	$	666	$	451
Sales and marketing	613		1,043		1,636		2,487
Research and development	490		288		1,456		546
General and administrative	975		735		2,848		1,766
Total stock-based compensation expense	$	2,309	$	2,285	$	6,606	$	5,250