Stockholders' Equity - Summary of Warrant Activities (Detail) - Warrants [Member] - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Class Of Warrant Or Right [Line Items]
Balance outstanding, Beginning, Number of Warrants	716,748	873,336
Warrants expired, Number of Warrants	(716,748)	(156,588)
Balance outstanding, Ending, Number of Warrants		716,748	873,336
Balance outstanding, Beginning, Weighted Average Exercise Price	$ 15.98	$ 17.79
Warrants expired, Weighted Average Exercise Price	$ 15.98	26.07
Balance outstanding, Ending, Weighted Average Exercise Price		$ 15.98	$ 17.79
Balance outstanding, Weighted Average Remaining Contractual Life (in years)		2 months 19 days	1 year