Consolidated Statements of Stockholders' Equity (Deficit) (USD $)	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Deficit Accumulated During the Development Stage [Member]
Beginning balance at Apr. 19, 2007
Issuance of common stock
Stock-based compensation expense
Net loss
Ending balance at Dec. 31, 2007
Ending balance, Shares at Dec. 31, 2007
Issuance of common stock to founders		2,000	(2,000)
Issuance of common stock to founders, Shares		1,730,000
Issuance of restricted common stock		12,000	(12,000)
Issuance of restricted common stock, Shares		12,628,000
Stock-based compensation expense	2,000		2,000
Net loss	(98,000)			(98,000)
Ending balance at Dec. 31, 2008	(96,000)	14,000	(12,000)	(98,000)
Ending balance, Shares at Dec. 31, 2008		14,358,000
Issuance of restricted common stock, Shares		130,000
Stock-based compensation expense	2,000		2,000
Net loss	(872,000)			(872,000)
Ending balance at Dec. 31, 2009	(966,000)	14,000	(10,000)	(970,000)
Ending balance, Shares at Dec. 31, 2009		14,488,000
Issuance of restricted common stock, Shares		219,000
Stock-based compensation expense	4,000		4,000
Net loss	(1,339,000)			(1,339,000)
Ending balance at Dec. 31, 2010	(2,301,000)	14,000	(6,000)	(2,309,000)
Ending balance, Shares at Dec. 31, 2010		14,707,000
Issuance of common stock through conversion of notes payable	3,490,000	8,000	3,482,000
Issuance of common stock through conversion of notes payable, Shares		7,677,000
Issuance of warrants to consultants/Warrants issued with convertible notes and conversion of notes	1,111,000		1,111,000
Stock option exercises, Shares
Issuance of restricted common stock, Shares		61,000
Beneficial conversion feature of convertible notes payable	239,000		239,000
Stock-based compensation expense	9,000		9,000
Net loss	(4,383,000)			(4,383,000)
Ending balance at Dec. 31, 2011	(1,835,000)	22,000	4,835,000	(6,692,000)
Ending balance, Shares at Dec. 31, 2011		22,445,000
Issuance of common stock in connection with the merger		6,000	(6,000)
Issuance of common stock in connection with the merger, Shares		6,000,000
Issuance of common stock through private placements in connection with reverse merger	13,723,000	14,000	13,709,000
Issuance of common stock through private placements in connection with reverse merger, Shares		13,723,000
Costs associated with the merger	(13,723,000)		(13,723,000)
Issuance of common stock through conversion of notes payable and accrued interest in connection with the merger	1,526,000	2,000	1,524,000
Issuance of common stock through conversion of notes payable and accrued interest in connection with the merger, Shares		1,525,000
Issuance of warrants to consultants/Warrants issued with convertible notes and conversion of notes	890,000		890,000
Issuance of common stock from warrant exercises, net	10,991,000	14,000	10,977,000
Issuance of common stock from warrant exercises, net, Shares	13,423,622	13,424,000
Warrant liability removed due to exercise of warrants	23,321,000		23,321,000
Stock option exercises	18,000		18,000
Stock option exercises, Shares	224,064	224,000
Issuance of restricted common stock		1,000	(1,000)
Issuance of restricted common stock, Shares		1,380,000
Restricted stock forfeitures
Restricted stock forfeitures, Shares		(186,000)
Stock-based compensation expense	1,435,000		1,435,000
Loss on inducement to exercise warrants	1,904,000		1,904,000
Net loss	(43,553,000)			(43,553,000)
Ending balance at Dec. 31, 2012	(5,303,000)	59,000	44,883,000	(50,245,000)
Ending balance, Shares at Dec. 31, 2012		58,535,000
Issuance of common stock from warrant exercises, net	3,724,000	6,000	3,718,000
Issuance of common stock from warrant exercises, net, Shares	6,131,198	6,131,000
Warrant liability removed due to exercise of warrants	23,869,000		23,869,000
Stock option exercises, Shares
Issuance of restricted common stock, Shares		55,000
Restricted stock forfeitures
Restricted stock forfeitures, Shares		(34,000)
Stock-based compensation expense	848,000		848,000
Expense related to modification of warrants	65,000		65,000
Warrant liability reclassified to equity	1,886,000		1,886,000
Net loss	(16,120,000)			(16,120,000)
Ending balance at Mar. 31, 2013	8,969,000	65,000	75,269,000	(66,365,000)
Ending balance, Shares at Mar. 31, 2013		64,687,000
Issuance of warrants to consultants/Warrants issued with convertible notes and conversion of notes	492,000		492,000
Issuance of common stock from warrant exercises, net	1,101,000	3,000	1,098,000
Issuance of common stock from warrant exercises, net, Shares	2,713,207	2,713,000
Warrant liability removed due to exercise of warrants	10,874,000		10,874,000
Stock option exercises	402,000		402,000
Stock option exercises, Shares	183,796	184,000
Issuance of restricted common stock, Shares		60,000
Restricted stock forfeitures
Restricted stock forfeitures, Shares		(215,000)
Issuance of common stock from public offering	46,915,000	10,000	46,905,000
Issuance of common stock from public offering, Shares		10,684,000
Stock-based compensation expense	4,600,000		4,600,000
Expense related to modification of warrants	12,000		12,000
Warrant liability reclassified to equity	767,000		767,000
Net loss	(25,848,000)			(25,848,000)
Ending balance at Mar. 31, 2014	$ 48,284,000	$ 78,000	$ 140,419,000	$ (92,213,000)
Ending balance, Shares at Mar. 31, 2014		78,113,000