Stockholders' Equity - Summary of Warrant Activities (Detail) - Warrants [Member] - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Class Of Warrant Or Right [Line Items]
Balance outstanding, Beginning, Number of Warrants	873,336	978,830
Warrants expired, Number of Warrants	(156,588)	(105,494)
Balance outstanding, Ending, Number of Warrants	716,748	873,336	978,830
Warrants exercisable at December 31, 2015, Number of Warrants	716,748
Balance outstanding, Beginning, Weighted Average Exercise Price	$ 17.79	$ 19.82
Warrants expired, Weighted Average Exercise Price	26.07	32.68
Balance outstanding, Ending, Weighted Average Exercise Price	15.98	$ 17.79	$ 19.82
Warrants exercisable at December 31, 2015, Weighted Average Exercise Price	$ 15.98
Balance outstanding, Weighted Average Remaining Contractual Life (in years)	2 months 19 days	1 year	1 year 10 months 24 days
Warrants exercisable at December 31, 2015, Weighted Average Remaining Contractual Life (in years)	2 months 19 days