Discontinued Operations - Assets and Liabilities of the Discontinued Operations (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Total current assets	$ 0	$ 6,308
Current liabilities:
Total current liabilities	$ 330	5,638
Test and Inspection Services | Discontinued Operations, Disposed of by Sale
Current assets:
Accounts receivable - net		4,959
Inventories - net		840
Other current assets		509
Total current assets		6,308
Property, plant, and equipment - net		21,879
Operating lease right-of-use assets - net		1,994
Other assets:
Other intangibles - net		1,401
Deferred tax assets		9,116
Other assets		83
Total assets		40,781
Current liabilities:
Accounts payable		3,332
Accrued payroll and employee benefits		902
Current maturities of long-term debt		28
Other accrued liabilities		1,376
Total current liabilities		5,638
Long-term debt		13
Long-term operating lease liabilities		1,256
Other long-term liabilities		4,342
Total liabilities		$ 11,249