CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Income [Member]
Balance at Dec. 31, 2017	$ 9,905	$ 45	$ 331,609	$ (322,585)	$ 836
Balance, shares at Dec. 31, 2017		45,256,999
Cumulative effect adjustment for adoption of new accounting principle	218			218
Net loss	(74,532)			(74,532)
Other comprehensive income	2				2
Issuance of stock, net of issue costs	40,938	$ 29	40,909
Issuance of stock, net of issue costs, shares		28,790,548
Fair value of warrants issued	355		355
Exercise of stock options	503		503
Exercise of stock options, shares		310,900
Vesting of stock units	(27)		(27)
Vesting of stock units, shares		153,601
Exercise of warrants	28,863	$ 21	28,842
Exercise of warrants , shares		20,184,224
Settlement of derivative liability	38,666		38,666
Stock-based compensation	2,814		2,814
Balance at Sep. 30, 2018	47,705	$ 95	443,671	(396,899)	838
Balance, shares at Sep. 30, 2018		94,696,272
Balance at Jun. 30, 2018	11,687	$ 74	374,766	(363,991)	838
Balance, shares at Jun. 30, 2018		74,512,048
Cumulative effect adjustment for adoption of new accounting principle	218			218
Net loss	(33,126)			(33,126)
Exercise of warrants	28,863	$ 21	28,842
Exercise of warrants , shares		20,184,224
Settlement of derivative liability	38,666		38,666
Stock-based compensation	1,397		1,397
Balance at Sep. 30, 2018	47,705	$ 95	443,671	(396,899)	838
Balance, shares at Sep. 30, 2018		94,696,272
Balance at Dec. 31, 2018	$ 37,633	$ 95	445,192	(408,493)	839
Balance, shares at Dec. 31, 2018	95,372,236	95,372,236
Net loss	$ (46,383)			(46,383)
Other comprehensive income	1				1
Issuance of stock, net of issue costs	20,755	$ 12	20,743
Issuance of stock, net of issue costs, shares		12,234,495
Exercise of stock options	308	$ 1	307
Exercise of stock options, shares		166,760
Vesting of stock units	(87)		(87)
Vesting of stock units, shares		255,753
Stock-based compensation	3,711		3,711
Balance at Sep. 30, 2019	$ 15,938	$ 108	469,866	(454,876)	840
Balance, shares at Sep. 30, 2019	108,029,244	108,029,244
Balance at Jun. 30, 2019	$ 28,210	$ 106	466,493	(439,229)	840
Balance, shares at Jun. 30, 2019		106,297,792
Net loss	(15,647)			(15,647)
Issuance of stock, net of issue costs	2,412	$ 2	2,410
Issuance of stock, net of issue costs, shares		1,707,995
Vesting of stock units	(14)		(14)
Vesting of stock units, shares		23,457
Stock-based compensation	977		977
Balance at Sep. 30, 2019	$ 15,938	$ 108	$ 469,866	$ (454,876)	$ 840
Balance, shares at Sep. 30, 2019	108,029,244	108,029,244