Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Contributed Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)
Beginning Balance, amount at Dec. 31, 2012	$ 12,068	$ 25	$ 31,245	$ (19,202)	$ 0
Beginning Balance (shares) at Dec. 31, 2012		25,332
Net loss	(15,282)			(15,282)
Issuance of common stock and warrants	19,912	$ 3	19,909
Issuance of common stock and warrants (shares)		2,488
Exercise of options	20,969	$ 14	20,955
Exercise of options and warrants (shares)		13,830
Unrealized gain on available-for-sale securities	22				22
Foreign currency translation adjustment	0
Equity-based compensation	3,828		3,828
Ending Balance, amount at Dec. 31, 2013	41,517	$ 42	75,937	(34,484)	22
Ending Balance (shares) at Dec. 31, 2013		41,650
Net loss	(30,933)			(30,933)
Issuance of common stock and warrants	44,875	$ 3	44,872
Issuance of common stock and warrants (shares)		2,678
Exercise of options	923		923
Exercise of options and warrants (shares)		312
Unrealized gain on available-for-sale securities	(15)				(15)
Foreign currency translation adjustment	0
Equity-based compensation	9,624		9,624
Ending Balance, amount at Dec. 31, 2014	65,991	$ 45	131,356	(65,417)	7
Ending Balance (shares) at Dec. 31, 2014		44,640
Net loss	(45,498)			(45,498)
Issuance of common stock and warrants	103,351	$ 6	103,345
Issuance of common stock and warrants (shares)		6,426
Exercise of options	805		805
Exercise of options and warrants (shares)		125
Unrealized gain on available-for-sale securities	(20)				(20)
Foreign currency translation adjustment	1				1
Equity-based compensation	8,388		8,388
Ending Balance, amount at Dec. 31, 2015	$ 133,018	$ 51	$ 243,894	$ (110,915)	$ (12)
Ending Balance (shares) at Dec. 31, 2015		51,191