Stockholders' Equity - Summary of Black-Scholes Options Pricing Model (Detail)	12 Months Ended
	Dec. 31, 2014
Series E Preferred Stock
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Dividend yield	0.00%
Series E Preferred Stock | Minimum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Expected volatility	58.00%
Expected life in years	9 years 10 months 24 days
Risk free interest rate	2.64%
Series E Preferred Stock | Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Expected volatility	60.00%
Expected life in years	10 years
Risk free interest rate	2.71%
Series D Preferred Stock
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Dividend yield	0.00%
Series D Preferred Stock | Minimum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Expected volatility	55.00%
Expected life in years	6 years 9 months 18 days
Risk free interest rate	1.91%
Series D Preferred Stock | Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Expected volatility	58.00%
Expected life in years	7 years
Risk free interest rate	2.64%