Equity Incentive Plans (Tables)

12 Months Ended

Dec. 31, 2017

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Schedule of Fair Value of Stock Option Grants Valuation Assumptions by Block-Scholes Option Pricing Model

The fair value of stock option grants is set forth below and was determined using the Black-Scholes option pricing model with the following assumptions:

	Year Ended December 31,
	2015	2016	2017
Fair value of common stock	$0.85	$0.85-$3.06	$3.06-$19.56
Expected term (in years)	2-10	2-10	5-6
Risk-free interest rate	0.75%-2.10%	0.75%-1.77%	1.85%-2.29%
Expected volatility	55%	55%	55%
Expected dividend yield	—	—	—

Schedule of Stock Option Activity

A summary of stock option activities under the 2005 Plan and 2017 Plan during the year ended December 31, 2017 is as follows:

	Number of Options Outstanding			Weighted Average Exercise Price
Outstanding at December 31, 2014		916,584		$	0.89
Granted		112,068		$	0.85
Exercised		(45,199	)	$	0.70
Canceled		(45,203	)	$	0.80
Outstanding at December 31, 2015		938,250		$	0.90
Granted		272,769		$	1.27
Exercised		(33,395	)	$	0.75
Canceled		(47,483	)	$	4.14
Outstanding at December 31, 2016		1,130,141		$	0.86
Granted		261,476		$	5.52
Exercised		(74,990	)	$	0.74
Canceled		(22,499	)	$	1.52
Outstanding at December 31, 2017		1,294,128		$	1.79

Schedule of Stock Options Outstanding, Exercisable and Vested

Stock options outstanding, exercisable and vested were as follows:

Outstanding at December 31, 2015		Weighted-average Remaining Contractual Life (years)	Exercisable and Vested as of December 31, 2015		Weighted-average Remaining Contractual Life (years)		Weighted-average Exercise Price
	938,250	6.31		731,516	5.79		0.94
Outstanding at December 31, 2016		Weighted-average Remaining Contractual Life (years)	Exercisable and Vested as of December 31, 2016		Weighted-average Remaining Contractual Life (years)		Weighted-average Exercise Price
	1,130,141	6.29		842,261	5.32		0.74
Outstanding at December 31, 2017		Weighted-average Remaining Contractual Life (years)	Exercisable and Vested as of December 31, 2017		Weighted-average Remaining Contractual Life (years)		Weighted-average Exercise Price
	1,294,128	6.22		883,959		5.00	0.85

Schedule of Stock-Based Compensation Expense Recorded in Consolidated Statements of Operations

Total stock-based compensation expense associated with the 2005 Plan, 2017 Plan and 2017 ESPP is recorded in the consolidated statements of operations and was allocated as follows (in thousands):

	Year Ended December 31,
	2015		2016		2017
Costs	$	13	$	11	$	75
Sales and marketing		13		7		133
Research and development		32		18		69
General and administrative		79		47		351
Total	$	137	$	83	$	628