CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (DEFICIT) - USD ($) shares in Thousands, $ in Thousands	Preffered Stock	Common Stock	Additional Paid-In Capital	Treasury Stock	Retained Earnings (Deficit)	Accumulated Other Comprehensive Loss	Total
Beginning Balance, Amount at Dec. 31, 2016	$ 0	$ 100	$ 244,309	$ 0	$ (358,393)	$ (79)	$ (114,063)
Beginning Balance, Shares at Dec. 31, 2016	0	10,016
Conversion of restricted stock units, Amount	$ 0	$ 1	(113)	0	0	0	(112)
Conversion of restricted stock units, Shares		44
Compensation expense on share-based awards	0	$ 0	2,491	0	0	0	2,491
Issuance of convertible debt, Amount	0	$ 11	12,499	0	0	0	$ 12,510
Issuance of convertible debt, Shares		1,100
Issuance of common stock upon the exercise of stock options, Shares							0
Net proceeds from sale of shares, Amount	0	$ 7	1,972	0	0	0	$ 1,979
Net proceeds from sale of shares, Shares		681
Other comprehensive income (loss)	0	$ 0	0	0	0	79	79
Net loss	0	0	0	0	(77,141)	0	(77,141)
Ending Balance, Amount at Dec. 31, 2017	$ 0	$ 119	261,158	0	(435,534)	0	(174,257)
Ending Balance, Shares at Dec. 31, 2017	0	11,841
Conversion of restricted stock units, Amount	$ 0	$ 0	(2)	0	0	0	(2)
Conversion of restricted stock units, Shares		33
Compensation expense on share-based awards	0	$ 0	885	0	0	0	885
Net proceeds from sale of shares, Amount	0	$ 2	451	0	0	0	453
Net proceeds from sale of shares, Shares		191
Other comprehensive income (loss)	0	$ 0	0	0	0	0	0
Net loss	0	0	0	0	(32,097)	0	(32,097)
Ending Balance, Amount at Jun. 30, 2018	$ 0	$ 121	$ 262,492	$ 0	$ (467,631)	$ 0	$ (205,018)
Ending Balance, Shares at Jun. 30, 2018	0	12,065