Stock Options, Stock Purchase Plan and Warrants - Summary of Warrant Activity (Detail) - Warrant [Member] - $ / shares		12 Months Ended
	Jan. 09, 2012	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Warrants outstanding, beginning balance		650,000	650,000	1,358,333
Warrants, Granted	200,000	0	0	0
Warrants, Exercised		(200,000)	0	(458,333)
Warrants, Expired		0	0	(250,000)
Warrants, Cancelled		0	0	0
Warrants outstanding, ending balance		450,000	650,000	650,000
Warrants exercisable, ending balance		450,000
Weighted Average Exercise Price Warrants outstanding, beginning balance		$ 1.48	$ 1.24	$ 1.24
Weighted average exercise price, granted	$ 1.43	0	0	0
Weighted Average Exercised Price, Exercised		0	0	0
Weighted Average Exercised Price, Expired		$ 0	$ 0	$ 0
Weighted Average Exercised Price, Cancelled		0	0	0
Weighted Average Exercised Price, Warrants outstanding, ending balance		$ 1.48	$ 1.48	$ 1.24
Weighted Average Exercised Price, Warrants exercisable, ending balance		$ 1.49