Recurring Fair Value Measurements - Summary of Quantitative Information with Respect to Valuation Methodology and Significant Unobservable Inputs Used for Company's Warrant Liabilities (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Stock Price	$ 1.20	$ 6.40
Risk-free Rate (5-year U.S. Treasury Yield)	1.65%	1.75%
Volatility (Annual)		93.43%
Time to Maturity (Years)		5 years 3 months 29 days
Maximum [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Volatility (Annual)	88.10%
Time to Maturity (Years)	4 years 3 months 29 days
Minimum [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Volatility (Annual)	72.90%
Time to Maturity (Years)	4 years 1 month 6 days