Stockholders' Equity, Equity Incentive Plans and Warrants (Summary of Restricted Stock Awards Activity) (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Options outstanding, number of shares	8,952,129	7,394,551
Options outstanding, weighted average exercise price	$ 2.93	$ 3.39
Options granted (in shares)	2,486,000
Options granted, weighted average exercise price	$ 0.89	$ 1.78	$ 0.97
Options forfeited (in shares)	(574,705)
Restricted Stock [Member]
Options outstanding, number of shares		2,233,563
Options outstanding, weighted average exercise price	$ 2.16	$ 2.09
Options granted (in shares)	843,968
Options granted, weighted average exercise price	$ 1.23
Options vested (in shares)	(1,915,270)
Options vested, weighted average exercise price	$ 1.72
Options forfeited (in shares)	(506,859)
Options forfeited, weighted average exercise price	$ 1.92
Options outstanding and unvested (in shares)		655,402