v2.4.0.8
Income Tax - Income Tax Computed at Federal Statutory Tax Rates (Detail)
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Income Tax Disclosure [Abstract]      
Federal statutory rate 35.00% 35.00% 35.00%
State income taxes-net of federal tax benefit 1.70% 2.80% 2.90%
Fair value derivative adjustments (11.70%) 10.70% (90.20%)
Change in valuation allowance (25.70%) (45.60%) 56.60%
Write off of deferred equity financing costs   (5.60%)  
Other (0.30%) (0.60%)  
Effective tax rate (1.00%) (3.30%) 4.30%