Consolidated Statements of Convertible Preferred Stock and Stockholders (Deficit) (Details 2) (USD $) In Thousands, except Share data, unless otherwise specified	Total	Convertible Preferred Stock
Balance at Apr. 26, 2007
Increase (Decrease) in Stockholders' Equity
Issuance of stock for cash, net of issuance costs		$ 1,541
Issuance of stock for cash, net of issuance costs (in shares)		1,655,435
Balance at Dec. 31, 2007		1,541
Balance (in shares) at Dec. 31, 2007		1,655,435
Increase (Decrease) in Stockholders' Equity
Issuance of stock for cash, net of issuance costs		12,914
Issuance of stock for cash, net of issuance costs (in shares)		12,953,751
Balance at Dec. 31, 2008		14,455
Balance (in shares) at Dec. 31, 2008		14,609,186
Increase (Decrease) in Stockholders' Equity
Issuance of stock for cash, net of issuance costs		32,354
Issuance of stock for cash, net of issuance costs (in shares)		16,244,180
Balance at Dec. 31, 2009		46,809
Balance (in shares) at Dec. 31, 2009		30,853,366
Balance at Dec. 31, 2010		46,809
Balance (in shares) at Dec. 31, 2010		30,853,366
Increase (Decrease) in Stockholders' Equity
Issuance of stock for cash, net of issuance costs		3,500
Issuance of stock for cash, net of issuance costs (in shares)		1,500,000
Balance at Dec. 31, 2011		50,309
Balance (in shares) at Dec. 31, 2011		32,353,366
Increase (Decrease) in Stockholders' Equity
Issuance of stock for cash, net of issuance costs		16,726
Issuance of stock for cash, net of issuance costs (in shares)		16,808,504
Conversion of convertible preferred stock into common stock	11,889	(11,889)
Conversion of convertible preferred stock into common stock (in shares)		(5,694,180)
Exchange of debt and common stock for Series B-1 preferred stock		1,380
Exchange of debt and common stock for Series B-1 preferred stock (in shares)		1,500,000
Balance at Dec. 31, 2012	56,526	56,526
Balance (in shares) at Dec. 31, 2012	44,967,690	44,967,690
Increase (Decrease) in Stockholders' Equity
Conversion of convertible preferred stock into common stock	$ 56,526	$ (56,526)
Conversion of convertible preferred stock into common stock (in shares)		(44,967,690)
Balance (in shares) at Dec. 31, 2013	0