CONSOLIDATED STATEMENTS OF STOCKOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Treasury Stock [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Loss [Member]
Balance at Dec. 31, 2015	$ 24,966	$ 300	$ 74,455	$ (49,114)	$ 1,662	$ (2,337)
Balance (in shares) at Dec. 31, 2015		29,979		(4,738)
Net loss attributable to common stockholders	(7,436)	$ 0	0	$ 0	(7,436)	0
Sale of common stock, net	880	$ 1	879	0	0	0
Sale of common stock, net (in shares)		120
Settlement of stock awards	(1,966)	$ 6	0	$ (1,972)	0	0
Settlement of stock awards (in shares)		581		(278)
Unrealized loss on pension liability	(824)	$ 0	0	$ 0	0	(824)
Stock-based compensation expense	7,806	0	7,806	0	0	0
Balance at Dec. 31, 2016	28,025	$ 307	87,521	$ (51,086)	(5,556)	(3,161)
Balance (in shares) at Dec. 31, 2016		30,680		(5,016)
Cumulative change in accounting principle	4,599	$ 0	4,381	$ 0	218	0
Net loss attributable to common stockholders	(2,021)	0	0	0	(2,021)	0
Sale of common stock, net	40,561	$ 55	40,506	0	0	0
Sale of common stock, net (in shares)		5,472
Settlement of stock awards	(2,574)	$ 6	0	$ (2,580)	0	0
Settlement of stock awards (in shares)		651		(335)
Unrealized loss on pension liability	429	$ 0	0	$ 0	0	429
Stock-based compensation expense	2,870	0	2,870	0	0	0
Balance at Dec. 31, 2017	67,290	$ 368	130,897	$ (53,666)	(7,577)	(2,732)
Balance (in shares) at Dec. 31, 2017		36,803		(5,351)
Net loss attributable to common stockholders	(7,889)	$ 0	0	$ 0	(7,889)	0
Settlement of stock awards	(1,088)	$ 4	0	$ (1,092)	0	0
Settlement of stock awards (in shares)		358		(163)
Unrealized loss on pension liability	(786)	$ 0	0	$ 0	0	(786)
Stock-based compensation expense	1,934	0	1,934	0	0	0
Balance at Dec. 31, 2018	$ 59,461	$ 372	$ 132,831	$ (54,758)	$ (15,466)	$ (3,518)
Balance (in shares) at Dec. 31, 2018		37,161		(5,514)