Common Stock (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011
Common Stock
Common stock, authorized shares	200,000	200,000	138,500
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01	$ 0.01
Common stock, issued shares	93,540		11,834
Common stock, outstanding shares	93,540		11,834
Shares reserved for future issuance
Conversion of Series B, Series C, Series D, Series E, Series F and Series G convertible preferred stock			66,256
Convertible preferred stock warrants			302
Common stock warrants	2,905		2,640
Equity compensation plans	17,455		17,617
Shares reserved for future issuance	20,360		86,815