Annual report pursuant to Section 13 and 15(d)

Net Loss Per Common Share - Computations of Diluted Weighted Average Shares Outstanding (Detail)

v2.4.0.8
Net Loss Per Common Share - Computations of Diluted Weighted Average Shares Outstanding (Detail)
 12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]      
Total of weighted average shares outstanding 5,090,171 3,371,161 10,206,543
Series A [Member]
      
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]      
Total of weighted average shares outstanding 0 0 3,796,733
Series B [Member]
      
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]      
Total of weighted average shares outstanding 0 0 2,158,935
Series C [Member]
      
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]      
Total of weighted average shares outstanding 0 0 1,966,635
Unvested Restricted Common Stock [Member]
      
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]      
Total of weighted average shares outstanding 0 0 0
Warrants to Purchase Common Stock [Member]
      
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]      
Total of weighted average shares outstanding 1,012,977 1,091,558 804,949
Options to Purchase Common Stock [Member]
      
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]      
Total of weighted average shares outstanding 3,936,199 2,279,603 1,479,291
Restricted Stock [Member]
      
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]      
Total of weighted average shares outstanding 140,995 0 0