Nature of the Business and Basis of Presentation - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands			12 Months Ended
	Jul. 02, 2015	Jun. 26, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Jul. 01, 2015
Nature Of Business And Basis Of Presentation [Line Items]
Entity incorporated year			Oct. 31, 2010
Entity incorporated state name			State of Delaware
Accumulated deficit			$ 174,191	$ 82,612
Cash, cash equivalents and investments			$ 229,995
Common Stock [Member]
Nature Of Business And Basis Of Presentation [Line Items]
Common stock issued and sold	8,545,138			8,545,138	6,563
Net proceeds from issuance of common stock from IPO after deducting underwriting discounts and commissions	$ 139,267
Conversion of redeemable convertible preferred stock into common stock		22,866,987		22,866,987
Initial Public Offering ("IPO") [Member] | Common Stock [Member]
Nature Of Business And Basis Of Presentation [Line Items]
Public offering price per share		$ 18.00				$ 18.00
Conversion of redeemable convertible preferred stock into common stock		22,866,987
Over-Allotment Option [Member] | Common Stock [Member]
Nature Of Business And Basis Of Presentation [Line Items]
Common stock issued and sold	1,114,583