Summary of Significant Accounting Policies - Additional Information (Details)				12 Months Ended
	Dec. 07, 2016 USD ($) $ / shares shares	Jul. 26, 2016 USD ($) $ / shares shares	Jun. 16, 2016	Dec. 31, 2018	Dec. 31, 2017 USD ($) shares	Dec. 31, 2016 USD ($) shares	Dec. 31, 2015 USD ($) shares	Jul. 20, 2016 USD ($) shares	Dec. 31, 2014 USD ($)
Significant Accounting Policies [Line Items]
Common stock, shares issued					20,973,000	20,336,000
Aggregate net proceeds from issuance of stock | $	$ 38,700,000	$ 68,500,000
Outstanding shares of redeemable convertible preferred stock converted into common stock					8,531,146			8,531,146
Warrants automatically converted into common stock								123,759
Reverse split of common stock					On June 16, 2016, our board of directors and stockholders approved an amendment to our certificate of incorporation to effect a reverse split of shares of our authorized, issued and outstanding common stock and redeemable convertible preferred stock at a 1-for-12 ratio.
Reverse stock split ratio			0.0833
Deferred offering costs | $		$ 4,100,000			$ 0	$ 0
Cumulative ownership change percentage					50.00%
Cumulative change in ownership period					3 years
Income tax examination years, description					Due to the presence of NOLs in most jurisdictions, our tax years remain open for examination by taxing authorities back to 2000
US federal corporate tax rate					34.00%	34.00%	34.00%
Expected dividend yield assumed					0.00%
Scenario Forecast
Significant Accounting Policies [Line Items]
US federal corporate tax rate				21.00%
Minimum
Significant Accounting Policies [Line Items]
Payment Terms					30 days
Maximum
Significant Accounting Policies [Line Items]
Payment Terms					120 days
US federal corporate tax rate					35.00%
Measurement period to implement the Tax Act effect					1 year
Allowance for Sales Returns
Significant Accounting Policies [Line Items]
Amount reserved for sales returns | $					$ 3,282,000	$ 63,000	$ 128,000		$ 151,000
Allowance for Sales Returns | Customer One
Significant Accounting Policies [Line Items]
Amount reserved for sales returns | $					$ 3,200,000
Common Stock
Significant Accounting Policies [Line Items]
Issuance of common stock					637,000	197,000	654,000
Carrying value of redeemable convertible preferred stock | $					$ 106,100,000			$ 106,100,000
Additional Paid-in Capital
Significant Accounting Policies [Line Items]
Carrying value of warrants | $								$ 505,000
IPO
Significant Accounting Policies [Line Items]
Initial public offering closing date		Jul. 26, 2016
Issuance of common stock		5,520,000
Common stock, share offering price | $ / shares		$ 14.00
IPO | Common Stock
Significant Accounting Policies [Line Items]
Issuance of common stock						7,047,000
Underwriters option
Significant Accounting Policies [Line Items]
Common stock, shares issued		720,000
Follow-on Public Offering
Significant Accounting Policies [Line Items]
Issuance of common stock	1,527,380
Common stock, share offering price | $ / shares	$ 27.00
Follow-on public offering closing date	Dec. 07, 2016