Basis of Presentation - Cumulative Effect of Changes in Consolidated Financial Statements (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Jan. 01, 2018	Dec. 31, 2017
ASSETS
Other current assets	$ 794		$ 794		$ 1,068	$ 998
Other assets	982		982		756	397
LIABILITIES AND STOCKHOLDERS' DEFICIT
Other current liabilities	4,220		4,220		5,487	5,529
Other long-term liabilities	149		149		215	268
Accumulated deficit	(195,296)		(195,296)		(184,990)	(185,324)
CONDENSED CONSOLIDATED STATEMENT OF OPERATIONS:
Revenues	10,275		21,610
Selling, general and administrative expenses	6,433	$ 5,281	13,284	$ 8,760
Net loss	(5,077)	$ (5,883)	(10,306)	$ (9,012)
Effect of Change Higher/(Lower)
ASSETS
Other current assets	54		54
Other assets	359		359
LIABILITIES AND STOCKHOLDERS' DEFICIT
Other current liabilities	36		36
Other long-term liabilities	53		53
Accumulated deficit	334		334
CONDENSED CONSOLIDATED STATEMENT OF OPERATIONS:
Revenues	92		6
Selling, general and administrative expenses	(18)		(16)
Net loss	74		(10)
Accounting Standards Update 2014-09 | Balances Without Adoption of ASC 606
ASSETS
Other current assets	740		740
Other assets	623		623
LIABILITIES AND STOCKHOLDERS' DEFICIT
Other current liabilities	4,184		4,184
Other long-term liabilities	96		96
Accumulated deficit	(194,962)		(194,962)
CONDENSED CONSOLIDATED STATEMENT OF OPERATIONS:
Revenues	10,183		21,604
Selling, general and administrative expenses	6,451		13,300
Net loss	$ (5,151)		$ (10,296)
Balance at December 31, 2017
ASSETS
Other current assets						998
Other assets						397
LIABILITIES AND STOCKHOLDERS' DEFICIT
Other current liabilities						5,529
Other long-term liabilities						268
Accumulated deficit						$ (185,324)
Adjustments due to ASC 606 | Accounting Standards Update 2014-09
ASSETS
Other current assets					70
Other assets					359
LIABILITIES AND STOCKHOLDERS' DEFICIT
Other current liabilities					(42)
Other long-term liabilities					(53)
Accumulated deficit					$ (334)