Stockholders' Equity - Shares Available (Details)	Mar. 31, 2013		Dec. 31, 2012
Stockholders Equity Note [Line Items]
Preferred stock, shares authorized	20,000,000		20,000,000
Shares, Outstanding	49,799,198		47,761,119
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number	655,389		693,672
Class of Warrant or Right, Outstanding	41,032,048		38,332,389
Common stock
Stockholders Equity Note [Line Items]
Common stock, shares authorized	149,900,000		149,900,000
Shares, Outstanding	49,799,198
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number	3,776,672	[1]
Class of Warrant or Right, Outstanding	41,032,047
Undesignated Shares Available	55,292,083
Series B common stock
Stockholders Equity Note [Line Items]
Common stock, shares authorized	100,000		100,000
Shares, Outstanding	49,998
Undesignated Shares Available	50,002
Preferred Stock [Member]
Stockholders Equity Note [Line Items]
Preferred stock, shares authorized	20,000,000
Undesignated Shares Available	20,000,000
Stock Incentive Plan 2011 [Member]
Stockholders Equity Note [Line Items]
Number of shares available for grant	3,121,283

[1] Includes all of the options outstanding plus 3,121,283 shares remaining that are available for issuance under the 2011 Plan.