Goodwill and Other Intangible Assets - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets
Amortization expense	$ 5,729	$ 6,445	$ 6,966
Finite-lived intangible assets, carrying value	36,897	42,113
Accumulated amortization	43,379	38,656
Customer relationships
Finite-Lived Intangible Assets
Finite-lived intangible assets, carrying value	20,355	22,152
Accumulated amortization	15,914	13,453
Customer relationships | Test and Inspection Services
Finite-Lived Intangible Assets
Finite-lived intangible assets, carrying value	1,893
Accumulated amortization	587
Non-compete agreements
Finite-Lived Intangible Assets
Fully amortized intangible asset	$ 1,232	2,830
Trademarks and trade names
Finite-Lived Intangible Assets
Fully amortized intangible asset		$ 723
Minimum
Finite-Lived Intangible Assets
Finite lived intangible asset, useful life	5 years
Maximum
Finite-Lived Intangible Assets
Finite lived intangible asset, useful life	25 years
Weighted Average
Finite-Lived Intangible Assets
Finite lived intangible asset, useful life	16 years
Weighted Average | Customer relationships
Finite-Lived Intangible Assets
Finite lived intangible asset, useful life	18 years	18 years