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Stockholders' Equity (Tables)
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12 Months Ended |
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Dec. 31, 2013
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| Disclosure of Compensation Related Costs, Share-based Payments [Abstract] |
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| Schedule of Share-based Compensation, Activity [Table Text Block] |
Share-based compensation expense included in the statements of operations was as follows: | | | Year Ended December 31, | | | | | 2013 | | 2012 | | 2011 | | | | | | | | | | | | | | | Research and development costs | | $ | 932,200 | | $ | 655,303 | | $ | 1,727,042 | | | General and administrative expenses | | | 1,399,201 | | | 955,542 | | | 1,606,057 | | | Total | | $ | 2,331,401 | | $ | 1,610,845 | | $ | 3,333,099 | | |
| Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block] |
A summary of stock option activity and related information for the year ended December 31, 2013 follows: | | | Number of Options | | Weighted-
Average
Exercise
Price | | Weighted-
Average
Remaining
Contractual
Life (in years) | | Aggregate
Intrinsic Value | | | | | | | | | | | | | | | | | | Outstanding at January 1, 2013 | | | 14,787,287 | | $ | 1.98 | | | 6.1 | | $ | 1,926,000 | | | Granted | | | 3,840,962 | | $ | 1.11 | | | | | | | | | Exercised | | | - | | $ | - | | | | | | | | | Forfeited/Expired | | | (51,042) | | $ | 2.72 | | | | | | | | | Outstanding at December 31, 2013 | | | 18,577,207 | | $ | 1.79 | | | 5.8 | | $ | 24,000,710 | | | | | | | | | | | | | | | | | | Exercisable at December 31, 2013 | | | 12,659,353 | | $ | 2.14 | | | 4.5 | | $ | 12,938,385 | | | | | | | | | | | | | | | | | | Vested and expected to vest at December 31, 2013 | | | 18,577,207 | | $ | 1.79 | | | 5.8 | | $ | 24,000,710 | | |
| Schedule of Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range [Table Text Block] |
| Range of Exercise Prices | | Number of Options
Outstanding | | Weighted-
Average
Exercise
Price | | Weighted-
Average
Remaining
Contractual
Life (in years) | | Aggregate
Intrinsic Value | | | $0.50 - $1.00 | | | 7,400,000 | | $ | 0.78 | | | 6.3 | | $ | 15,734,000 | | | $1.01 - $2.00 | | | 4,296,837 | | $ | 1.19 | | | 7.6 | | | 7,381,481 | | | $2.01 - $3.00 | | | 2,077,037 | | $ | 2.48 | | | 5.4 | | | 885,229 | | | $3.01 - $4.00 | | | 4,803,333 | | $ | 3.59 | | | 3.7 | | | - | | | | | | 18,577,207 | | $ | 1.79 | | | 5.8 | | $ | 24,000,710 | | |
| Schedule Of Share Based Payment Award Stock Options Valuation Assumptions Black Sholes Model [Table Text Block] |
Significant assumptions used in this model include: | | | Year Ended December 31, | | | | | 2013 | | 2012 | | 2011 | | | | | | | | | | | | | | | Annual dividend | | | - | | | - | | | - | | | Expected life (in years) | | | 3.0 - 6.5 | | | 2.0 - 4.0 | | | 2.0 - 3.5 | | | Risk free interest rate | | | 0.29% - 2.43% | | | 0.24% - 0.65% | | | 0.25% - 1.39% | | | Expected volatility | | | 65.1% - 77.5% | | | 55.5% - 77.4% | | | 66.9% - 75.4% | | |
| Schedule of Share-based Compensation, Restricted Stock Units Award Activity [Table Text Block] |
A summary of our RSU activity for the years ended December 31, 2013 follows: | | | Number of
RSU's | | Weighted-
Average
Grant Date
Fair Value | | | Outstanding at January 1, 2013 | | | 371,491 | | $ | 2.10 | | | Granted | | | 30,702 | | $ | 1.14 | | | Vested and converted to common shares | | | - | | $ | - | | | Forfeited | | | (568) | | $ | 1.19 | | | Outstanding at December 31, 2013 | | | 401,625 | | $ | 2.03 | | | | | | | | | | | | Exercisable at December 31, 2013 | | | 389,465 | | $ | 2.06 | | |
| Schedule Of Share Based Compensation Warrant Activity [Table Text Block] |
A summary of warrant activity for the year ended December 31, 2013 follows: | | | Number of
Warrants | | Weighted-
Average
Exercised
Price | | Weighted-
Average
Remaining
Contractual Life
(in years) | | Aggregate
Intrinsic
Value | | | | | | | | | | | | | | | | | | Outstanding at January 1, 2013 | | | 19,840,176 | | $ | 2.08 | | | 3.5 | | $ | 854,649 | | | | | | | | | | | | | | | | | | Granted | | | 7,761,211 | | $ | 1.83 | | | 4.0 | | | | | | Exercised | | | (5,302,935) | | $ | 1.30 | | | | | | | | | Forfeited | | | (2,711,633) | | $ | 3.10 | | | | | | | | | Outstanding at December 31, 2013 | | | 19,586,819 | | $ | 1.96 | | | 3.4 | | $ | 21,146,495 | | | | | | | | | | | | | | | | | | Exercisable at December 31, 2013 | | | 17,992,219 | | $ | 1.80 | | | 3.0 | | $ | 19,695,409 | | |