Common Stock - Additional Information (Detail) - USD ($)	1 Months Ended	3 Months Ended	6 Months Ended	12 Months Ended
	Dec. 31, 2013	Jun. 30, 2016	Jun. 30, 2016	Dec. 31, 2015	Feb. 29, 2016
Components Of Common Stock [Line Items]
Common Stock, shares outstanding		52,016,432	52,016,432	51,998,306
Common Stock, shares authorized		100,000,000	100,000,000	100,000,000
Common Stock, par value		$ 0.0001	$ 0.0001	$ 0.0001
Preferred Stock, shares authorized		10,000,000	10,000,000	10,000,000
Preferred Stock, par value		$ 0.0001	$ 0.0001	$ 0.0001
Remaining common stocks and warrants under shelf registration		$ 86,300,000	$ 86,300,000
Maximum aggregate offering price of equity securities					$ 25,000,000
Non Employee Directors [Member] | Common Stock [Member]
Components Of Common Stock [Line Items]
Issuance of common stock for services, shares			18,126	7,998
Issuance of common stock for services			$ 60,000	$ 30,000
Shelf Registration [Member]
Components Of Common Stock [Line Items]
Common stock and warrants	$ 100,000,000
Common stock to be sold by directors and management in future public offerings	1,500,000
Agreement [Member]
Components Of Common Stock [Line Items]
Percentage of commission					3.00%
Gross proceeds from issuance of common stock		$ 0