Nature Of Business And Summary Of Significant Accounting Policies (Schedule Of Weighted-Average Shares That Have Been Excluded From The Number Of Shares Used To Calculate Basic And Diluted Net Loss Per Share) (Details) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted-average shares that have been excluded from the number of shares used to calculate basic and diluted net loss per share	14,227	12,508	11,312
Warrants To Purchase Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted-average shares that have been excluded from the number of shares used to calculate basic and diluted net loss per share	991	1,113	1,651
Stock Options And Restricted Stock Units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted-average shares that have been excluded from the number of shares used to calculate basic and diluted net loss per share	13,236	11,395	9,661