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Summary of Significant Accounting Policies (Detail) - Anti-dilutive Securities
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6 Months Ended | 12 Months Ended | |||
|---|---|---|---|---|---|
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Jun. 30, 2012
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Jun. 30, 2011
|
Dec. 31, 2011
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Dec. 31, 2010
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Dec. 31, 2009
|
|
| Anti-dilutive Securities | 16,657,470 | 12,723,219 | 8,640,434 | 7,187,391 | 3,515,816 |
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Stock Options [Member]
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|||||
| Anti-dilutive Securities | 6,111,127 | 3,762,477 | 3,679,977 | 3,762,477 | 669,777 |
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Warrant [Member]
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|||||
| Anti-dilutive Securities | 6,258,648 | 435,986 | 1,922,944 | 435,986 | 410,542 |
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Convertible Preferred Shares [Member]
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|||||
| Anti-dilutive Securities | 1,991,250 | 1,991,250 | 1,991,250 | ||
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Shares Under Convertible Note Agreements [Member]
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|||||
| Anti-dilutive Securities | 1,046,263 | 997,678 | 444,247 | ||