Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 42,015	$ 48,626
Accounts receivable (net of allowance of $712 and $671 at December 31, 2020 and 2019, respectively)	16,562	18,441
Notes receivable	22,775
Inventories	1,974	2,573
Prepaids and other current assets	4,780	5,164
Total current assets	88,106	74,804
Property, plant and equipment, at cost	312,532	343,893
Less accumulated depreciation	(300,573)	(325,440)
Property, plant and equipment, net	11,959	18,453
Operating lease right-of-use assets	20,406	21,371
Intangible assets, net	64	319
Deferred income taxes, net	76	50
Long-term note receivable		22,400
Other assets	2,604	3,648
Total assets	123,215	141,045
Current liabilities:
Accounts payable	7,759	6,103
Accrued compensation and benefits	5,754	7,407
Other accrued expense	5,075	5,930
Contract liabilities	12,896	12,098
Total current liabilities	31,484	31,538
Long-term pension liabilities	18,520	23,039
Long-term operating lease liabilities	21,890	23,120
Other post-employment benefits	1,372	1,347
Other liabilities	3,541	4,264
Total liabilities	76,807	83,308
Shareholders' equity:
Preferred stock, $.01 par value; Authorized 2,000,000 shares; none issued
Treasury stock, Series A, at cost; 1,913,860 shares held at December 30, 2020 and 2019	(13,443)	(13,443)
Additional paid-in capital	494,389	494,389
Accumulated other comprehensive loss	(32,468)	(32,294)
Accumulated deficit	(402,303)	(391,148)
Total shareholders’ equity	46,408	57,737
Total liabilities and shareholders’ equity	123,215	141,045
Series A [Member]
Shareholders' equity:
Common stock, $.01 par value; Authorized 125,000,000 shares	209	209
Series B [Member]
Shareholders' equity:
Common stock, $.01 par value; Authorized 125,000,000 shares	$ 24	$ 24