Condensed Consolidated Statement of Stockholders' Equity (Unaudited) - 9 months ended Sep. 30, 2018 - USD ($) shares in Thousands, $ in Thousands	At-the-market Offering [Member] Common Stock [Member]	At-the-market Offering [Member] Common Stock Subscribed [Member]	At-the-market Offering [Member] Additional Paid-in Capital [Member]	At-the-market Offering [Member] Receivables from Stockholder [Member]	At-the-market Offering [Member]	Public Offering [Member] Common Stock [Member]	Public Offering [Member] Common Stock Subscribed [Member]	Public Offering [Member] Additional Paid-in Capital [Member]	Public Offering [Member] Retained Earnings [Member]	Public Offering [Member] AOCI Attributable to Parent [Member]	Public Offering [Member] Receivables from Stockholder [Member]	Public Offering [Member] Treasury Stock [Member]	Common Stock [Member]	Common Stock Subscribed [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Receivables from Stockholder [Member]	Treasury Stock [Member]	Total
Balance (in shares) at Dec. 31, 2017													71,325	320					(200)
Balance at Dec. 31, 2017													$ 93		$ 609,829	$ (541,586)	$ (33)	$ (2,109)	$ (2,741)	$ 63,453
Net loss																(52,953)				(52,953)
Foreign currency translation adjustments																	(60)			(60)
Stock-based compensation expense															4,301					$ 4,301
Issuance of common stock (in shares)	4,230	(320)				9,091
Issuance of common stock	$ 5		$ 27,539	$ 2,109	$ 29,653	$ 12		$ 69,975
Exercise of stock options (in shares)													96							96
Exercise of stock options															467					$ 467
Balance (in shares) at Sep. 30, 2018													84,742						(200)
Balance at Sep. 30, 2018													$ 110		$ 712,111	(594,504)	$ (93)		$ (2,741)	114,883
Cumulative effect of ASU 2014-09 adoption																$ 35				$ 35