Discontinued Operations - Net Sales and Losses from Discontinued Operations (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
	Sep. 04, 2020	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss from discontinued operations before income taxes		$ (13,478)	$ (1,475)	$ (23,565)	$ (2,964)
Income tax benefit		3,730	785	5,509	1,509
Loss from discontinued operations		(9,748)	(690)	(18,056)	(1,455)
Test and Inspection Services
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss from discontinued operations	$ (10,034)
Test and Inspection Services | Discontinued Operations, Disposed of by Sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net sales		2,520	9,428	13,590	30,581
Loss from discontinued operations before income taxes		(306)	(1,475)	(10,393)	(2,964)
Income tax benefit		592	785	2,371	1,509
Loss on the sale of discontinued operations		(13,172)	0	(13,172)	0
Income tax benefit on the sale of discontinued operations		3,138	0	3,138	0
Loss from discontinued operations		$ (9,748)	$ (690)	$ (18,056)	$ (1,455)