Stock-Based Compensation (Summary of Option Activity) (Details) (USD $)	3 Months Ended
	Mar. 31, 2013
2005 Stock Incentive Plan [Member]
Stock Options
Outstanding at January 1, 2013	9,143,825
Granted	3,347,500
Exercised	(1,500)
Canceled	(355,458)
Outstanding at March 31, 2013	12,134,367
Shares exercisable at March 31, 2013	4,442,548
Shares available for grant at March 31, 2013	2,760,319
Weighted-Average Exercise Price
Outstanding at January 1, 2013	$ 1.87
Granted	$ 1.83
Exercised	$ 0.56
Canceled	$ 1.62
Outstanding at March 31, 2013	$ 1.87
Options exercisable, March 31, 2013	$ 2.18
1995 Stock Option Plan [Member]
Stock Options
Outstanding at January 1, 2013	211,900
Granted
Exercised
Canceled
Outstanding at March 31, 2013	211,900
Shares exercisable at March 31, 2013	211,900
Weighted-Average Exercise Price
Outstanding at January 1, 2013	$ 4.94
Granted
Exercised
Canceled
Outstanding at March 31, 2013	$ 4.94
Options exercisable, March 31, 2013	$ 4.94