Consolidated Statements of Changes in Stockholders' Equity (Deficit) (USD $) In Thousands, except Share data, unless otherwise specified	Total	Series A Convertible Preferred Stock	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Balance at Dec. 31, 2009	$ (6,156)	$ 49	$ 2	$ 49,114	$ 2	$ (55,323)
Balance (in shares) at Dec. 31, 2009		49,000,000	1,584,012
Increase (Decrease) in Stockholders' Equity
Exercise of stock options	4			4
Exercise of stock options (in shares)			8,750
Stock-based compensation	297			297
Net income (loss)	(38,463)					(38,463)
Other comprehensive income (loss)	(2)				(2)
Balance at Dec. 31, 2010	(44,320)	49	2	49,415		(93,786)
Balance (in shares) at Dec. 31, 2010		49,000,000	1,592,762
Increase (Decrease) in Stockholders' Equity
Exercise of stock options	29			29
Exercise of stock options (in shares)			69,559
Stock-based compensation	(82)			(82)
Net income (loss)	53,815					53,815
Other comprehensive income (loss)	1				1
Balance at Dec. 31, 2011	9,443	49	2	49,362	1	(39,971)
Balance (in shares) at Dec. 31, 2011		49,000,000	1,662,321
Increase (Decrease) in Stockholders' Equity
Issuance of Employee Stock Purchase Plan shares	223			223
Issuance of Employee Stock Purchase Plan shares (in shares)			36,727
Exercise of stock options	265			265
Exercise of stock options (in shares)			159,264
Warrant Exercise	1,156			1,156
Warrant Exercise (in shares)			64,309
Issuance of common stock, net of underwriters' discount and offering costs	92,382		17	92,365
Issuance of common stock, net of underwriters' discount and offering costs (in shares)			16,449,250
Conversion of preferred stock to common stock		(49)	12	37
Conversion of preferred stock to common stock (in shares)		(49,000,000)	12,249,998
Stock-based compensation	443			443
Net income (loss)	(46,284)					(46,284)
Other comprehensive income (loss)	(58)				(58)
Balance at Dec. 31, 2012	$ 57,570		$ 31	$ 143,851	$ (57)	$ (86,255)
Balance (in shares) at Dec. 31, 2012			30,621,869