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Stock options and warrants (Schedule of Stock-based Compensation) (Details) (USD $)
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3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
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Jun. 30, 2014
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Jun. 30, 2013
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Jun. 30, 2014
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Jun. 30, 2013
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| Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items] | ||||
| Stock options to employees and directors | $ 326,235 | $ 410,529 | $ 729,074 | $ 894,154 |
| Stock options to consultants for APPY1 activities | 157 | 597 | 339 | 1,193 |
| Stock-based compensation | 326,392 | 411,126 | 729,413 | 895,347 |
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Selling, general and administrative expenses [Member]
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| Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items] | ||||
| Stock-based compensation | 305,351 | 372,692 | 688,345 | 809,735 |
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Research and development expenses [Member]
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| Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items] | ||||
| Stock-based compensation | $ 21,041 | $ 38,434 | $ 41,068 | $ 85,612 |