Income Taxes - Reconciliation of Federal Statutory Income Tax Rate (Detail)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Tax Disclosure [Abstract]
Federal statutory income tax rate	34.00%	34.00%	34.00%
State taxes, net of federal benefit	3.45%	3.45%	3.45%
Permanent differences-derivative loss (gain)	0.11%	110.51%	7.02%
Permanent differences-other	(1.07%)	44.12%	(2.76%)
Research and development ("R&D") credit	4.91%	(129.12%)	2.92%
Other	0.64%	(30.89%)	(6.63%)
Valuation allowance	(42.04%)	(24.82%)	(38.00%)
Federal statutory income tax rate, Total	0.00%	7.25%	0.00%