CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (DEFICIT) - USD ($) shares in Thousands, $ in Thousands	Preferred Stock	Common Stock	Additional Paid-In Capital	Treasury Stock	Retained Earnings (Deficit)	Accumulated Other Comprehensive Loss	Total
Beginning Balance, Amount at Dec. 31, 2015	$ 0	$ 61,000	$ 227,387	$ (5,548)	$ (188,803)	$ 0	$ 33,097
Beginning Balance, Shares at Dec. 31, 2015	0	6,111
Conversion of restricted stock units, Amount	$ 0	$ 0	0	(23)	0	0	(23)
Conversion of restricted stock units, Shares	0	4
Reclassification of treasury stock	$ 0	$ 0	(5,571)	5,571	0	0	0
Compensation expense on share-based awards	0	0	2,718	0	0	0	2,718
Net proceeds from sale of shares, Amount	$ 0	$ 39	19,775	0	0	0	19,814
Net proceeds from sale of shares, Shares	0	3,901
Other comprehensive income (loss)	$ 0	$ 0	0	0	0	(79)	(79)
Net loss	0	0	0	0	(169,590)	0	(169,590)
Ending Balance, Amount at Dec. 31, 2016	$ 0	$ 100	244,309	0	(358,393)	(79)	(114,063)
Ending 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	0	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	0	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	0	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