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Warrants and Derivative Liabilities - Schedule of Assumptions Used to Calculate the Fair Value of Warrants (Detail) (USD $) In Millions, unless otherwise specified | 3 Months Ended | 0 Months Ended | 3 Months Ended | 0 Months Ended | 3 Months Ended
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Dec. 31, 2013 | Sep. 30, 2013 | Jun. 30, 2013 | Mar. 31, 2013 | Sep. 30, 2014 Senior Convertible Note Warrant | Jun. 30, 2014 Senior Convertible Note Warrant | Mar. 31, 2014 Senior Convertible Note Warrant | Dec. 31, 2013 Senior Convertible Note Warrant | Sep. 30, 2013 Senior Convertible Note Warrant | Jun. 30, 2013 Senior Convertible Note Warrant | Mar. 31, 2013 Senior Convertible Note Warrant | Oct. 09, 2013 Senior Convertible Note Warrant Post Modification | Oct. 09, 2013 Senior Convertible Note Warrant Pre Modification | Sep. 30, 2014 Senior Secured Term Loan First Warrant | Jun. 30, 2014 Senior Secured Term Loan First Warrant | Mar. 31, 2014 Senior Secured Term Loan First Warrant | Dec. 31, 2013 Senior Secured Term Loan First Warrant | Sep. 30, 2013 Senior Secured Term Loan First Warrant | Jun. 30, 2013 Senior Secured Term Loan First Warrant | Mar. 31, 2013 Senior Secured Term Loan First Warrant | Nov. 15, 2013 Senior Secured Term Loan First Warrant Post Modification | Nov. 15, 2013 Senior Secured Term Loan First Warrant Pre Modification | Nov. 15, 2013 Senior Secured Term Loan Second Warrant | Sep. 30, 2014 Senior Secured Term Loan Second Warrant | Jun. 30, 2014 Senior Secured Term Loan Second Warrant | Mar. 31, 2014 Senior Secured Term Loan Second Warrant | Dec. 31, 2013 Senior Secured Term Loan Second Warrant
Derivative [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Risk-free interest rate | 0.12% | 0.10% | 0.21% | 0.20% | 1.07% | 0.98% | 1.11% | 1.17% | 1.02% | 1.13% | 0.67% | 1.05% | 1.05% | 1.13% | 1.04% | 1.18% | 1.24% | 1.09% | 1.20% | 0.70% | 1.00% | 1.00% | 1.55% | 1.65% | 1.57% | 1.76% | 1.89%
Expected annual dividend yield | 16.50% | 15.50% | 16.70% | 16.50% | 0.00% | 0.00% | 0.00% | 0.00% | 0.00% | 0.00% | 0.00% | 0.00% | 0.00% | 0.00% | 0.00% | 0.00% | 0.00% | 0.00% | 0.00% | 0.00% | 0.00% | 0.00% | 0.00% | 0.00% | 0.00% | 0.00% | 0.00%
Expected volatility | 68.63% | 66.26% | 65.80% | 66.91% | 76.20% | 83.50% | 80.99% | 75.60% | 71.98% | 71.90% | 71.74% | 71.45% | 71.45% | 78.30% | 82.75% | 80.73% | 74.79% | 72.10% | 72.30% | 72.01% | 72.64% | 72.64% | 76.97% | 78.10% | 80.00% | 79.73% | 80.37%
Term (years) | 9 months | 1 year | 1 year 3 months 4 days | 1 year 6 months 4 days | 3 years 4 days | 3 years 3 months 4 days | 3 years 6 months 4 days | 3 years 9 months 4 days | 4 years 4 days | 4 years 3 months 7 days | 4 years 6 months 4 days | 3 years 11 months 27 days | 3 years 11 months 27 days | 3 years 2 months 5 days | 3 years 5 months 5 days | 3 years 8 months 5 days | 3 years 11 months 5 days | 4 years 2 months 5 days | 4 years 5 months 5 days | 4 years 8 months 5 days | 4 years 18 days | 4 years 18 days | 5 years 5 months 27 days | 4 years 7 months 13 days | 4 years 10 months 13 days | 5 years 1 month 13 days | 5 years 4 months 13 days
Fair value |  |  |  |  | $ 1.5 | $ 2.3 | $ 2.2 | $ 2.2 | $ 2.5 | $ 3.0 | $ 3.4 | $ 3.2 | $ 2.2 | $ 0.1 | $ 0.1 | $ 0.1 | $ 0.1 | $ 0.2 | $ 0.2 | $ 0.2 | $ 0.1 | $ 0.1 | $ 0.3 | $ 0.2 | $ 0.3 | $ 0.3 | $ 0.3

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- Definition Expected dividends to be paid to holders of the underlying shares or financial instruments (expressed as a percentage of the share or instrument's price). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258 + Details
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- Definition Period the instrument, asset or liability is expected to be outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258 + Details
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- Definition Measure of dispersion, in percentage terms (for instance, the standard deviation or variance), for a given stock price. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258 + Details
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- Definition Risk-free interest rate assumption used in valuing an instrument. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258 + Details
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