Stock-Based Compensation (Summary of Option Activity)(Details) (USD $)	12 Months Ended
	Dec. 31, 2012
2005 Stock Incentive Plan [Member]
Stock Options
Outstanding at January 1, 2012	7,412,746
Granted	3,483,000
Exercised	(90,534)
Canceled	(1,661,387)
Outstanding at December 31, 2012	9,143,825
Vested and expected to vest at December 31, 2012	8,255,692
Shares exercisable at December 31, 2012	3,541,268
Shares available for grant at December 31, 2012	5,752,361
Weighted-Average Exercise Price
Outstanding at January 1, 2012	$ 2.22
Granted	$ 1.29
Exercised	$ 0.61
Canceled	$ 2.27
Outstanding at December 31, 2012	$ 1.87
Vested and expected to vest at December 31, 2012	$ 1.92
Options exercisable, December 31, 2012	$ 2.34
1995 Stock Option Plan [Member]
Stock Options
Outstanding at January 1, 2012	474,650
Granted
Exercised
Canceled	(262,750)
Outstanding at December 31, 2012	211,900
Vested and expected to vest at December 31, 2012	211,900
Shares exercisable at December 31, 2012	211,900
Weighted-Average Exercise Price
Outstanding at January 1, 2012	$ 4.38
Granted
Exercised
Canceled	$ 3.86
Outstanding at December 31, 2012	$ 4.94
Vested and expected to vest at December 31, 2012	$ 4.94
Options exercisable, December 31, 2012	$ 4.94