Consolidated Statements of Changes in Stockholder's Equity - USD ($) $ in Thousands	Total	Common Stock	Series D convertible preferred stock	Series E-1 convertible preferred stock	Series E-2 convertible preferred stock	Series E-1 and E-2 preferred stock warrants	Common Stock Warrant	Preferred Stock Convertible Preferred Stock	Preferred Stock Series D convertible preferred stock	Preferred Stock Series E-1 convertible preferred stock	Preferred Stock Series E-2 convertible preferred stock	Common Stock	Additional Paid-in Capital	Additional Paid-in Capital Common Stock	Additional Paid-in Capital Series D convertible preferred stock	Additional Paid-in Capital Series E-1 convertible preferred stock	Additional Paid-in Capital Series E-2 convertible preferred stock	Additional Paid-in Capital Series E-1 and E-2 preferred stock warrants	Additional Paid-in Capital Common Stock Warrant	Retained Earnings	AOCI Attributable to Parent	Restricted Stock Common Stock
Beginning balance at Dec. 31, 2012	$ 43,095							$ 0				$ 0	$ 217,631							$ (174,485)	$ (51)
Preferred stock, shares outstanding, beginning balance (in shares) at Dec. 31, 2012								38,503,591
Common stock, shares outstanding, beginning balance (in shares) at Dec. 31, 2012												3,827,267
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock, exercised options (in shares)												333,911
Adjustments to additional paid in capital, share-based compensation, stock options	521												521
Stock issued during period, shares, new issues (in shares)										5,801,250	3,506,875
Stock issued during period, value, new issues				$ 49,465	$ 25,000											$ 49,465	$ 25,000
Warrants issued	1,533			1,533												1,533
Stock-based compensation expense	2,337			5,257	12								2,337			5,257	12
Net loss	(47,889)																			(47,889)
Foreign currency translation adjustments	167																				167
Ending balance at Dec. 31, 2013	$ 68,960							$ 0				$ 0	291,218							(222,374)	116
Preferred stock, shares outstanding, ending balance (in shares) at Dec. 31, 2013								47,811,716
Common stock, shares outstanding, ending balance (in shares) at Dec. 31, 2013	4,161,178											4,161,178
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock, exercised options (in shares)												124,986
Adjustments to additional paid in capital, share-based compensation, stock options	$ 121												121
Stock issued during period, shares, new issues (in shares)										2,806,480
Stock issued during period, value, new issues	22,452												22,452
Warrants issued	177					$ 42												$ 42
Stock issued during period, shares, warrants exercised									367,456
Stock issued during period, value, warrants exercised	2,205												2,205
Stock-based compensation expense	2,550			302			$ 134						2,550			302			$ 134
Net loss	(45,722)																			(45,722)
Foreign currency translation adjustments	(613)																				(613)
Ending balance at Dec. 31, 2014	$ 49,827							$ 0				$ 0	318,420							(268,096)	(497)
Preferred stock, shares outstanding, ending balance (in shares) at Dec. 31, 2014	0							50,985,652
Common stock, shares outstanding, ending balance (in shares) at Dec. 31, 2014	4,286,164											4,286,164
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock, exercised options (in shares)												383,458
Adjustments to additional paid in capital, share-based compensation, stock options	$ 806												806
Stock issued during period, shares, new issues (in shares)	10,350,000											10,350,000										174,530
Stock issued during period, value, new issues	$ 139,766												139,766
Warrants issued	$ 0
Stock issued during period, shares, warrants exercised									321,854	300,059	200,996	11,734
Stock issued during period, value, warrants exercised		$ 18	$ 450	$ 2,400	$ 1,608									$ 18	$ 450	$ 2,400	$ 1,608
Issuance of common stock - preferred stock conversion to common stock	(2,590,241)							(51,808,561)				(25,904,241)
Stock-based compensation expense	$ 3,607												3,607
Net loss	(57,246)																			(57,246)
Foreign currency translation adjustments	(24)																				(24)
Ending balance at Dec. 31, 2015	$ 141,212							$ 0				$ 0	$ 467,075							$ (325,342)	$ (521)
Preferred stock, shares outstanding, ending balance (in shares) at Dec. 31, 2015	0							0
Common stock, shares outstanding, ending balance (in shares) at Dec. 31, 2015	41,110,127											41,110,127