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Supplemental financial information - Earnings Per Share (Details)
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12 Months Ended |
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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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| Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |
|
|
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| Anti-dilutive shares excluded from the computation of net loss per share |
2,416,800 |
11,772,362 |
10,040,333 |
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Series A Preferred Stock [Member]
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|
|
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| Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |
|
|
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| Anti-dilutive shares excluded from the computation of net loss per share |
0 |
2,914,187 |
2,914,187 |
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Series B Preferred Stock [Member]
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|
|
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| Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |
|
|
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| Anti-dilutive shares excluded from the computation of net loss per share |
0 |
7,232,092 |
5,572,000 |
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Equity Option [Member]
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|
|
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| Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |
|
|
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| Anti-dilutive shares excluded from the computation of net loss per share |
2,388,394 |
1,617,875 |
1,545,938 |
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Common Stock Warrants [Member] | Warrant [Member]
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|
|
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| Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |
|
|
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| Anti-dilutive shares excluded from the computation of net loss per share |
28,406 |
8,208 |
8,208 |