Stockholders' Equity (Schedule of Stock Options Activity) (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Weighted-Average Remaining Contractual Term
Compensation cost	$ 1,300,000
Unrecognized share-based compensation expense related to unvested awards expected to be recognized in the period	1 year 9 months
Stock Options [Member]
Shares
Outstanding, beginning balance	6,225,612	6,292,982	5,339,413
Granted	240,000	852,139	1,934,566
Exercised	(61,756)	(31,474)	(44,464)
Forfeited	(390,694)	(888,035)	(936,533)
Expired	(39,123)
Outstanding, ending balance	5,974,039	6,225,612	6,292,982	5,339,413
Exercisable, December 31, 2013	4,589,956
Vested and expected to vest, December 31, 2013	5,809,558
Weighted Average Exercise Price
Outstanding, beginning balance	$ 2.52	$ 2.74	$ 3.18
Granted	$ 1.65	$ 1.22	$ 1.71
Exercised	$ 1.21	$ 1.24	$ 2.66
Forfeited	$ 2.20	$ 2.91	$ 3.07
Expired	$ 2.96
Outstanding, ending balance	$ 2.52	$ 2.52	$ 2.74	$ 3.18
Exercisable, December 31, 2013	$ 2.75
Vested and expected to vest, December 31, 2013	$ 2.54
Weighted-Average Remaining Contractual Term
Outstanding	6 years 6 months	7 years 4 months 24 days	8 years	8 years 3 months 18 days
Exercisable	6 years
Vested and expected to vest	6 years 6 months