Assumptions Used in Black Scholes Pricing Model for New Grants (Detail)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Volatility, minimum	73.04%	69.38%	64.22%
Volatility, maximum	78.70%	77.92%	72.65%
Risk-Free Interest Rates, minimum	1.54%	1.81%	1.01%
Risk-Free Interest Rates, maximum	1.93%	2.02%	2.10%
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected Term (in years)	5 years 6 months	5 years 6 months	5 years 6 months
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected Term (in years)	6 years 3 months	6 years 3 months	6 years 3 months