Summary of Significant Accounting Policies - Additional Information (Details)			3 Months Ended		9 Months Ended
	Jul. 26, 2016 USD ($) $ / shares shares	Jun. 16, 2016	Sep. 30, 2016 USD ($) shares	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($) shares	Sep. 30, 2015 USD ($)	Jul. 20, 2016 USD ($) shares	Jul. 01, 2016 USD ($)	Dec. 31, 2015 shares
Significant Accounting Policies [Line Items]
Common stock, shares issued | shares			18,780,000		18,780,000				4,382,000
Aggregate net proceeds from issuance of stock					$ 68,808,000
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 our authorized, issued and outstanding common stock and redeemable convertible preferred stock at a 1-for-12 ratio per share.
Reverse stock split ratio		0.0833
Cost of product revenue			$ 14,574,000	$ 9,988,000	$ 37,408,000	$ 26,889,000
Research and development expense			6,622,000	4,304,000	17,782,000	12,488,000
Sales and marketing expense			5,584,000	3,772,000	15,902,000	10,151,000
General and administrative expense			3,356,000	1,938,000	8,214,000	5,089,000
Net income			808,000	$ 13,000	(1,776,000)	$ 82,000
Capitalized deferred offering costs	$ 3,400,000
Accounting Standards Update March 2016
Significant Accounting Policies [Line Items]
Adjustment to accumulated deficit								$ 215,000
Reclassifications
Significant Accounting Policies [Line Items]
Cost of product revenue			26,000		72,000
Research and development expense			115,000		324,000
Sales and marketing expense			48,000		134,000
General and administrative expense			(189,000)		(530,000)
Net income			$ 0		$ 0
IPO
Significant Accounting Policies [Line Items]
Initial public offering closing date					Jul. 26, 2016
Common stock, share offering price | $ / shares	$ 14.00
Common stock, shares issued | shares	720,000
Outstanding shares of redeemable convertible preferred stock converted into common stock | shares							8,522,837
Warrants automatically converted into common stock | shares							56,409
IPO | Common Stock
Significant Accounting Policies [Line Items]
Initial public offering of shares of common | shares	5,520,000
Aggregate net proceeds from issuance of stock	$ 68,500,000
Carrying value of redeemable convertible preferred stock							$ 104,200,000
IPO | Additional Paid-in Capital
Significant Accounting Policies [Line Items]
Carrying value of warrants							$ 2,300,000