Fair Value Measurements, Warrant Liabilities, Changes in Level 3, and Outstanding Debt (Details) (USD $)	3 Months Ended		12 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Reclassification of contingent warrant liability to equity upon exercise of warrants	$ 0	$ (2,525,000)
Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Outstanding debt	47,189,000		35,308,000
Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Outstanding debt	47,668,000		36,461,000
Warrant Liabilities [Member]
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Risk-free interest rate (in hundredths)	0.55%
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	31,828,000	69,869,000	69,869,000
Reclassification of contingent warrant liability to equity upon exercise of warrants	0	(2,525,000)
Net increase (decrease) in estimated fair value of contingent warrant liabilities upon revaluation	40,000	(20,002,000)
Ending balance	31,868,000	47,342,000
Warrant Liabilities [Member] | Minimum [Member]
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Expected volatility (in hundredths)	73.90%		69.60%
Risk-free interest rate (in hundredths)			0.03%
Expected term	1 year 8 months 8 days		0 years 1 month 2 days
Warrant Liabilities [Member] | Maximum [Member]
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Expected volatility (in hundredths)	74.80%		72.90%
Risk-free interest rate (in hundredths)			0.67%
Expected term	1 year 11 months 8 days		2 years 2 months 8 days
Foreign Exchange Option [Member] | Maximum [Member]
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Estimated fair value of the foreign exchange options	$ 100