Net Loss Per Share (Details) - shares
shares in Thousands
12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]      
Securities outstanding that could potentially dilute per share data 16,195 22,748 23,286
Stock Options Outstanding [Member]      
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]      
Securities outstanding that could potentially dilute per share data 16,195 14,704 14,712
Warrants Outstanding [Member]      
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]      
Securities outstanding that could potentially dilute per share data   8,044 8,574