Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2016

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Unvested Shares of Common Stock Activity

The following table summarizes activity of unvested shares of our common stock for the year ended December 31, 2016:

	SHARES OUTSTANDING
	NUMBER OF SHARES			WEIGHTED- AVERAGE EXERCISE PRICE PER SHARE
	(in thousands, except per share amounts)
Outstanding at January 1, 2016		136		$	1.76
Issued		59			5.35
Vested		(77	)		2.15
Outstanding at December 31, 2016		118		$	3.30

Summary of Stock Option Activity

The following table summarizes option award activity for the year ended December 31, 2016:

				WEIGHTED-		WEIGHTED-
	NUMBER OF			AVERAGE		AVERAGE
	SHARES			EXERCISE		REMAINING		TOTAL
	UNDERLYING			PRICE PER		CONTRACTUAL		INTRINSIC
	OPTIONS			SHARE		LIFE (YEARS)		VALUE
	(in thousands, except per share amounts)
Outstanding at January 1, 2016		1,896		$	3.72		7.77	$	8,666
Granted		707			20.59
Exercised		(196	)		3.05
Forfeited or cancelled		(97	)		6.28
Outstanding at December 31, 2016		2,310			8.84		7.68		61,203
Vested and exercisable December 31, 2016		1,067		$	2.69		6.15	$	34,831

Schedule of Stock Options Valuation Assumptions

In determining the fair value of stock awards granted, the following weighted-average assumptions were used in the Black-Scholes option pricing model for awards granted in the periods indicated:

	EMPLOYEE STOCK PURCHASE PLAN		STOCK OPTIONS
	YEAR ENDED DECEMBER 31,		YEAR ENDED DECEMBER 31,
	2016		2016	2015	2014
Risk-free interest rates		0.4%	1.1% – 1.4%	1.2% – 1.6%	1.8% – 2.0%
Expected term	0.5 years		4.3 – 6.1 years	4.3 – 6.0 years	6.0 years
Expected dividends yield	None		None	None	None
Volatility		61.8%	40.8% – 49.5%	41.5% – 43.4%	43.8% – 46.9%

Summary of Stock-Based Compensation Expense

Stock-Based Compensation Expense

The following table presents the detail of stock-based compensation expense amounts included in our consolidated statements of operations for the periods indicated:

	YEAR ENDED DECEMBER 31,
	2016		2015		2014
	(in thousands)
Cost of revenue	$	96	$	31	$	49
Research and development expense		983		305		362
Sales and marketing expense		1,289		692		413
General and administrative expense		397		150		313
Offering costs		—		—		38
Total stock-based compensation expense	$	2,765	$	1,178	$	1,175