CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands		Common Stock	Additional Paid-In Capital	Treasury Stock	Accumulated Deficit	Accumulated Other Comprehensive Loss	Total
Balance at Dec. 31, 2018		$ 372	$ 132,831	$ (54,758)	$ (16,080)	$ (3,518)	$ 58,847
Balance (in shares) at Dec. 31, 2018		37,161		(5,514)
Changes in Stockholders' Equity
Net (loss) income attributable to common stockholders		$ 0	0	$ 0	(5,292)	0	(5,292)	[1]
Settlement of stock awards		$ 4	0	$ (776)	0	0	(772)
Settlement of stock awards (in shares)		451		(187)
Unrealized gain on pension liability		$ 0	0	$ 0	1,648	344	1,992
Stock-based compensation expense		0	1,386	0	0	0	1,386
Stock buy-back		$ 0	0	$ (197)	0	0	(197)
Stock buy-back (in shares)		0		(30)
Balance at Dec. 31, 2019	[1]	$ 376	134,217	$ (55,731)	(19,724)	(3,174)	55,964
Balance (in shares) at Dec. 31, 2019	[1]	37,612		(5,731)
Changes in Stockholders' Equity
Net (loss) income attributable to common stockholders		$ 0	0	$ 0	4,333	0	4,333	[1]
Settlement of stock awards		$ 5	0	$ (701)	0	0	(696)
Settlement of stock awards (in shares)		543		(222)
Unrealized gain on pension liability		$ 0	0	$ 0	0	1,015	1,015
Stock-based compensation expense		0	1,163	0	0	0	1,163
Stock-based consulting fees		$ 2	598	0	0	0	600
Stock-based consulting fees (in shares)		190
Stock buy-back		$ 0	0	$ (359)	0	0	(359)
Stock buy-back (in shares)				(220)
Balance at Dec. 31, 2020	[1]	$ 383	135,978	$ (56,791)	(15,391)	(2,159)	62,020
Balance (in shares) at Dec. 31, 2020	[1]	38,345		(6,173)
Changes in Stockholders' Equity
Net (loss) income attributable to common stockholders					(7,419)		(7,419)
Settlement of stock awards		$ 5		$ (375)			(370)
Settlement of stock awards (in shares)		496		(225)
Unrealized gain on pension liability						119	119
Stock-based compensation expense			173				173
Balance at Mar. 31, 2021		$ 388	136,151	$ (57,166)	(22,810)	(2,040)	54,523
Balance (in shares) at Mar. 31, 2021		38,841		(6,398)
Balance at Dec. 31, 2020	[1]	$ 383	135,978	$ (56,791)	(15,391)	(2,159)	62,020
Balance (in shares) at Dec. 31, 2020	[1]	38,345		(6,173)
Changes in Stockholders' Equity
Net (loss) income attributable to common stockholders					(13,853)		(13,853)
Settlement of stock awards		$ 6		$ (375)			(369)
Settlement of stock awards (in shares)		508		(225)
Unrealized gain on pension liability						237	237
Stock-based compensation expense			351				351
Balance at Jun. 30, 2021		$ 389	136,329	$ (57,166)	(29,244)	(1,922)	48,386
Balance (in shares) at Jun. 30, 2021		38,853		(6,398)
Balance at Dec. 31, 2020	[1]	$ 383	135,978	$ (56,791)	(15,391)	(2,159)	62,020
Balance (in shares) at Dec. 31, 2020	[1]	38,345		(6,173)
Changes in Stockholders' Equity
Net (loss) income attributable to common stockholders					(17,461)		(17,461)
Settlement of stock awards		$ 5		$ (375)			(370)
Settlement of stock awards (in shares)		521		(225)
Unrealized gain on pension liability						356	356
Sale of common stock		$ 2	165				167
Sale of common stock (in shares)		150
Stock-based compensation expense			529				529
Balance at Sep. 30, 2021		$ 390	136,672	$ (57,166)	(32,852)	(1,803)	45,241
Balance (in shares) at Sep. 30, 2021		39,016		(6,398)
Balance at Dec. 31, 2020	[1]	$ 383	135,978	$ (56,791)	(15,391)	(2,159)	62,020
Balance (in shares) at Dec. 31, 2020	[1]	38,345		(6,173)
Changes in Stockholders' Equity
Net (loss) income attributable to common stockholders		$ 0	0	$ 0	(20,805)	0	(20,805)
Settlement of stock awards		$ 5	0	$ (375)	0	0	(370)
Settlement of stock awards (in shares)		535		(225)
Unrealized gain on pension liability		$ 0	0	$ 0	0	816	816
Sale of common stock		$ 42	7,597	0	0	0	7,639
Sale of common stock (in shares)		4,144
Stock-based compensation expense		$ 0	707	$ 0	0	0	707
Stock buy-back (in shares)		0		0
Balance at Dec. 31, 2021		$ 430	144,282	$ (57,166)	(36,196)	(1,343)	50,007
Balance (in shares) at Dec. 31, 2021		43,024		(6,398)
Balance at Mar. 31, 2021		$ 388	136,151	$ (57,166)	(22,810)	(2,040)	54,523
Balance (in shares) at Mar. 31, 2021		38,841		(6,398)
Changes in Stockholders' Equity
Net (loss) income attributable to common stockholders					(6,434)		(6,434)
Settlement of stock awards		$ 1					1
Settlement of stock awards (in shares)		12
Unrealized gain on pension liability						118	118
Stock-based compensation expense			178				178
Balance at Jun. 30, 2021		$ 389	136,329	$ (57,166)	(29,244)	(1,922)	48,386
Balance (in shares) at Jun. 30, 2021		38,853		(6,398)
Changes in Stockholders' Equity
Net (loss) income attributable to common stockholders					(3,608)		(3,608)
Settlement of stock awards (in shares)		13
Unrealized gain on pension liability						119	119
Sale of common stock		$ 1	165				166
Sale of common stock (in shares)		150
Stock-based compensation expense			178				178
Balance at Sep. 30, 2021		$ 390	$ 136,672	$ (57,166)	$ (32,852)	$ (1,803)	$ 45,241
Balance (in shares) at Sep. 30, 2021		39,016		(6,398)

[1] Amounts are revised. See Note 3 for more information.