Statements of Convertible Preferred Stock and Stockholders' Deficit (USD $) In Thousands, except Share data, unless otherwise specified	Total USD ($)	Common Stock	Additional Paid-In-Capital USD ($)	Accumulated Deficit USD ($)	Series A-1 Convertible Preferred Stock USD ($)	Series A-2 Convertible Preferred Stock USD ($)	Series A-3 Convertible Preferred Stock USD ($)	Series A-4 Convertible Preferred Stock USD ($)	Series A-5 Convertible Preferred Stock USD ($)	Series A-6 Convertible Preferred Stock USD ($)
Balance at Dec. 31, 2012	$ (200,661)			$ (200,661)	$ 71,957	$ 86,714	$ 11,182	$ 271	$ 525
Balance (in shares) at Dec. 31, 2012		867,204			939,612	983,208	142,227	3,998	6,443
Increase (Decrease) in Stockholders' Equity
Net loss	(8,305)			(8,305)
Accretion of dividends on preferred stock	(3,582)		(334)	(3,248)	1,630	1,706	246
Stock-based compensation expense	334		334
Balance at Mar. 31, 2013	$ (212,214)			$ (212,214)	$ 73,587	$ 88,420	$ 11,428	$ 271	$ 525	$ 0
Balance (in shares) at Mar. 31, 2013		867,204			939,612	983,208	142,227	3,998	6,443