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Selected Quarterly Data (Details) (USD $)
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3 Months Ended | 12 Months Ended | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
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Dec. 31, 2013
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Sep. 30, 2013
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Jun. 30, 2013
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Mar. 31, 2013
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Dec. 31, 2012
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Sep. 30, 2012
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Jun. 30, 2012
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Mar. 31, 2012
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Dec. 31, 2013
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Dec. 31, 2012
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Dec. 31, 2011
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| Effect of Fourth Quarter Events [Line Items] | |||||||||||
| Revenues | $ 2,500 | $ 2,500 | $ 2,500 | $ 102,500 | $ 2,500 | $ 170,833 | $ 78,125 | $ 156,250 | $ 110,000 | $ 407,708 | $ 390,625 |
| Operating loss | (2,762,573) | (3,633,986) | (3,235,602) | (2,891,780) | (2,726,826) | (2,583,159) | (2,383,255) | (2,463,216) | (12,523,941) | (10,156,456) | (12,990,470) |
| Net loss | $ (3,303,188) | $ (6,686,957) | $ (6,251,630) | $ (3,590,087) | $ (2,714,964) | $ (2,577,391) | $ (2,376,381) | $ (2,452,781) | $ (19,831,862) | $ (10,121,517) | $ (12,518,527) |
| Net loss per share - basic and diluted (in dollars per share) | $ (0.04) | $ (0.09) | $ (0.09) | $ (0.05) | $ (0.04) | $ (0.04) | $ (0.04) | $ (0.05) | $ (0.27) | $ (0.17) | $ (0.26) |