Consolidated Statements of Equity (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Total Stockholders' Equity	Common Stock	Capital in Excess of Par Value	Accum-ulated Deficit	Common Stock Held in Treasury	Noncontrolling Interests in Subsidiaries
Balance at Dec. 31, 2018	$ 146,651	$ 123,986	$ 93	$ 186,256	$ (41,103)	$ (21,260)	$ 22,665
Balance (in shares) at Dec. 31, 2018			9,288			1,124
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercised and issued stock-based awards	15	15		15
Exercised and issued stock-based awards (in shares)			43
Stock-based compensation	234	234		234
Forfeited dividends	11	11		11
Tender of shares for stock-based awards	(249)	(249)				$ (249)
Tender of shares for stock-based awards (in shares)						9
Purchase of noncontrolling interest in consolidated subsidiary	(4,589)						(4,589)
Total comprehensive loss		(4,487)			(4,487)		(3)
Total comprehensive loss	(4,490)
Balance at Sep. 30, 2019	137,583	119,510	$ 93	186,516	(45,590)	$ (21,509)	18,073
Balance (in shares) at Sep. 30, 2019			9,331			1,133
Balance at Jun. 30, 2019	140,512	122,437	$ 93	186,334	(42,630)	$ (21,360)	18,075
Balance (in shares) at Jun. 30, 2019			9,305			1,128
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercised and issued stock-based awards	15	15		15
Exercised and issued stock-based awards (in shares)			26
Stock-based compensation	156	156		156
Forfeited dividends	11	11		11
Tender of shares for stock-based awards	(149)	(149)				$ (149)
Tender of shares for stock-based awards (in shares)						5
Total comprehensive loss		(2,960)			(2,960)		(2)
Total comprehensive loss	(2,962)
Balance at Sep. 30, 2019	137,583	119,510	$ 93	186,516	(45,590)	$ (21,509)	18,073
Balance (in shares) at Sep. 30, 2019			9,331			1,133
Balance at Dec. 31, 2019	134,082	121,099	$ 93	186,082	(43,567)	$ (21,509)	12,983
Balance (in shares) at Dec. 31, 2019			9,330			1,133
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercised and issued stock-based awards	22	22		22
Exercised and issued stock-based awards (in shares)			28
Stock-based compensation	516	516		516
Tender of shares for stock-based awards	(91)	(91)				$ (91)
Tender of shares for stock-based awards (in shares)						4
Total comprehensive loss		(12,014)			(12,014)		(1,601)
Total comprehensive loss	(13,615)
Balance at Sep. 30, 2020	120,914	109,532	$ 93	186,620	(55,581)	$ (21,600)	11,382
Balance (in shares) at Sep. 30, 2020			9,358			1,137
Balance at Jun. 30, 2020	135,987	124,412	$ 93	186,422	(40,503)	$ (21,600)	11,575
Balance (in shares) at Jun. 30, 2020			9,347			1,137
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercised and issued stock-based awards	22	22		22
Exercised and issued stock-based awards (in shares)			11
Stock-based compensation	176	176		176
Total comprehensive loss		(15,078)			(15,078)		(193)
Total comprehensive loss	(15,271)
Balance at Sep. 30, 2020	$ 120,914	$ 109,532	$ 93	$ 186,620	$ (55,581)	$ (21,600)	$ 11,382
Balance (in shares) at Sep. 30, 2020			9,358			1,137