Notes Payable - Additional Information (Detail) - USD ($)		1 Months Ended		12 Months Ended
	Jan. 31, 2012	Oct. 31, 2013	Nov. 30, 2010	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Debt Instrument [Line Items]
Interests for payments at a fixed rate				8.25%
Interest rate of final payment				4.50%
Number of common stock received		44,566
Notes Payable to Banks [Member]
Debt Instrument [Line Items]
Interest expense					$ 61,000	$ 228,000
Lighthouse Capital Partners VI, L.P [Member]
Debt Instrument [Line Items]
Borrowing capacity	$ 5,000,000		$ 5,000,000
Borrowed under loan agreement	100,000
Increments under loan agreement	$ 0		$ 0	$ 0	$ 0	$ 0
Commitment Termination Date				Jan. 31, 2012
Debt instrument interest only period				6 months
Interests for payments at a fixed rate of a periodic time				36 months
Series A Redeemable Convertible Preferred Stock [Member]
Debt Instrument [Line Items]
Warrant exercisable for common stock				200,000			200,000
Purchase price per share				$ 1.00
Convertible Preferred Stock [Member]
Debt Instrument [Line Items]
Warrant exercisable for common stock				50,000
Purchase price per share				$ 4.00