Summary of Warrants and Related Information (Detail) - Warrant - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Warrants
Outstanding	20,000	20,000	190,000
Exercised	0	0	(170,000)
Outstanding	20,000	20,000	20,000
Exercisable at December 31, 2016	20,000
Weighted Average Exercise Price
Outstanding	$ 6.64	$ 6.64	$ 19.80
Exercised			21.35
Outstanding	6.64	$ 6.64	$ 6.64
Exercisable at December 31, 2016	$ 6.64