Selected Quarterly Financial Data (unaudited) (Details) (USD $)	3 Months Ended	12 Months Ended
Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Selected quarterly financial data (unaudited)
Revenues	$ 2,866,371us-gaap_SalesRevenueNet	$ 4,332,104us-gaap_SalesRevenueNet	$ 4,439,820us-gaap_SalesRevenueNet	$ 5,332,539us-gaap_SalesRevenueNet	$ 5,613,559us-gaap_SalesRevenueNet	$ 6,251,325us-gaap_SalesRevenueNet	$ 6,742,242us-gaap_SalesRevenueNet	$ 5,793,726us-gaap_SalesRevenueNet	$ 16,970,834us-gaap_SalesRevenueNet	$ 24,400,852us-gaap_SalesRevenueNet	$ 28,844,513us-gaap_SalesRevenueNet
Cost of net revenues	303,601us-gaap_CostOfRevenue	333,828us-gaap_CostOfRevenue	338,519us-gaap_CostOfRevenue	312,828us-gaap_CostOfRevenue	313,310us-gaap_CostOfRevenue	471,200us-gaap_CostOfRevenue	579,466us-gaap_CostOfRevenue	2,332,960us-gaap_CostOfRevenue
Loss from operations	(4,366,992)us-gaap_OperatingIncomeLoss	(2,077,621)us-gaap_OperatingIncomeLoss	(3,754,279)us-gaap_OperatingIncomeLoss	(3,246,930)us-gaap_OperatingIncomeLoss	(3,611,657)us-gaap_OperatingIncomeLoss	(2,895,031)us-gaap_OperatingIncomeLoss	(3,432,071)us-gaap_OperatingIncomeLoss	(10,157,219)us-gaap_OperatingIncomeLoss	(13,445,822)us-gaap_OperatingIncomeLoss	(20,095,978)us-gaap_OperatingIncomeLoss	(33,764,682)us-gaap_OperatingIncomeLoss
Net loss	$ (3,685,704)	$ (2,105,859)	$ (3,795,530)	$ (3,293,505)	$ (3,676,389)	$ (2,943,823)	$ (3,490,297)	$ (10,213,755)	$ (12,880,598)	$ (20,324,264)	$ (33,962,548)
Net loss per common share - basic and diluted (in dollars per share)	$ (0.07)us-gaap_EarningsPerShareBasicAndDiluted	$ (0.05)us-gaap_EarningsPerShareBasicAndDiluted	$ (0.09)us-gaap_EarningsPerShareBasicAndDiluted	$ (0.09)us-gaap_EarningsPerShareBasicAndDiluted	$ (0.11)us-gaap_EarningsPerShareBasicAndDiluted	$ (0.09)us-gaap_EarningsPerShareBasicAndDiluted	$ (0.12)us-gaap_EarningsPerShareBasicAndDiluted	$ (0.39)us-gaap_EarningsPerShareBasicAndDiluted	$ (0.30)us-gaap_EarningsPerShareBasicAndDiluted	$ (0.68)us-gaap_EarningsPerShareBasicAndDiluted	$ (1.41)us-gaap_EarningsPerShareBasicAndDiluted

The aggregate cost of goods produced and sold and services rendered during the reporting period.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.2)

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 2

-Article 5

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- Definition

The amount of net income or loss for the period per each share in instances when basic and diluted earnings per share are the same amount and reported as a single line item on the face of the financial statements. Basic earnings per share is the amount of net income or loss for the period per each share of common stock or unit outstanding during the reporting period. Diluted earnings per share includes the amount of net income or loss for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

+ References

No definition available.

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- Definition

Net income after adjustments for dividends on preferred stock (declared in the period) and/or cumulative preferred stock (accumulated for the period).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 260

-SubTopic 10

-Section 45

-Paragraph 11

-URI http://asc.fasb.org/extlink&oid=7655603&loc=d3e1377-109256

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- Definition

The net result for the period of deducting operating expenses from operating revenues.

+ References

No definition available.

+ Details

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- Definition

Total revenue from sale of goods and services rendered during the reporting period, in the normal course of business, reduced by sales returns and allowances, and sales discounts.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.1)

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

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-Paragraph 1

-Article 5

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