Nature of the Business and Summary of Significant Accounting Policies - Additional Information (Detail)	3 Months Ended	12 Months Ended
	Sep. 30, 2015 USD ($)	Dec. 31, 2015 USD ($) Segment Region	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Number of operating segments | Segment		1
Number of geographic regions | Region		1
Original maturities		Three months or less
Restricted cash		$ 685,000	$ 685,000
Impairment of goodwill	$ 0
Advertising expenses		$ 1,000,000
Performance period		5 years
Tax incentive awarded		$ 3,800,000
State research and development tax credits monetized		3,400,000
Amount of benefit recognized		$ 700,000	400,000	$ 300,000
Short-term debt issuance cost			100,000
Long-term debt issuance cost			$ 100,000
Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Expected remaining maturities period of marketable securities classified as available-for-sale		3 months