Valuation Techniques and Unobservable Inputs Applied to Level Three Fair Value Measurements (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Common Stock Warrant Liability
Fair Value Inputs Liabilities Quantitative Information [Line Items]
Valuation Technique	Monte Carlo Simulation
Volatility	49.90%	52.00%
Expected term	4 years 4 months 24 days	5 years 9 months 18 days
Equity raise price discount assumption	15.00%	15.00%
Significant Unobservable Inputs (Level 3) | Common Stock Warrant Liability
Fair Value Inputs Liabilities Quantitative Information [Line Items]
Estimated Fair Value, Liabilities	$ 6.9	$ 5.6
Valuation Technique	Monte Carlo Simulation
Volatility	49.90%	52.00%
Expected term	4 years 4 months 24 days	5 years 9 months 18 days
Equity Raise Probability	60.00%	25.00%
Equity raise price discount assumption	15.00%
Issue Price Discount To Fair Value		15.00%
Significant Unobservable Inputs (Level 3) | Redeemable Preferred Stock
Fair Value Inputs Liabilities Quantitative Information [Line Items]
Estimated Fair Value, Liabilities	$ 18.7
Valuation Technique	Discounted cash flow
Fair Value Inputs Credit Spread	17.50%
Fair Value Inputs Redemption Period	56 months