Stockholders' Equity - Schedule of Share-Based Compensation, Stock Options, Activity (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Equity [Abstract]
Total Stock Options Outstanding, Beginning balance	5,016,916
Total Stock Options Outstanding, Granted	903,775
Total Stock Options Outstanding, Exercised	(9,681)
Total Stock Options Outstanding, Forfeited, Canceled	(346,177)
Total Stock Options Outstanding, Ending balance	5,564,833	5,016,916
Weighted Average Exercise Price per Share, Beginning balance	$ 4.54
Weighted Average Exercise Price per Share, Granted	$ 1.67
Weighted Average Exercise Price per Share, Exercised	$ 1.28
Weighted Average Exercise Price per Share, Forfeited, Canceled	$ 3.53
Weighted Average Exercise Price per Share, Ending balance	$ 4.14	$ 4.54
Nonvested Stock Options, Beginning balance	404,500
Nonvested Stock Options, Granted	903,775
Nonvested Stock Options, Vested	(513,296)
Nonvested Stock Options, Forfeited, Canceled	(200,500)
Nonvested Stock Options, Ending balance	594,479	404,500
Weighted Average Grant Date Fair Value per Share, Beginning balance	$ 2.30
Weighted Average Grant Date Fair Value per Share, Granted	$ 1.21	$ 1.32	$ 4.04
Weighted Average Grant Date Fair Value per Share, Vested	$ 1.73
Weighted Average Grant Date Fair Value per Share, Forfeited, Canceled	$ 1.21
Weighted Average Grant Date Fair Value per Share, Ending balance	$ 1.50	$ 2.30