Stock-Based Awards - Summary of Option Activity (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Options, beginning balance	5,330,070	7,844,691	12,760,191
Options, Granted	0	0	0
Options, Forfeitures or expirations			(40,000)
Options, Exercised	(3,785,473)	(2,514,621)	(4,875,500)
Options, ending balance	1,544,597	5,330,070	7,844,691
Weighted Average Exercise Price of Options, beginning balance	$ 1.61	$ 1.29	$ 0.95
Weighted Average Exercise Price of Options, Granted	0	0	0
Weighted Average Exercise Price of Options, Forfeitures or expirations			4.11
Weighted Average Exercise Price of Options, Exercised	1.19	0.61	0.38
Weighted Average Exercise Price of Options, ending balance	$ 2.62	$ 1.61	$ 1.29