Income Taxes - Reconciliation Of Income Tax Rates (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Effective Income Tax Rate Reconciliation, Amount
Statutory rate	$ 2,936	$ 5,069	$ (5,159)
Foreign tax rate differential	65	129	156
State income taxes, net of federal benefit	1,003	83	(700)
Non-deductible expenses	181	278	219
Tax benefits related to disposition of the Test and Inspection Services business	(16,282)	0	0
Global intangible low-taxed income, net of tax credits	621	145	171
Income tax credits	(1,357)	(126)	(633)
Nondeductible executive compensation	132	234	351
Tax on unremitted foreign earnings	174	216	149
Change in valuation allowance	731	(29,966)	11,400
Other	(45)	103	63
Total income tax expense	$ (11,841)	$ (23,835)	$ 6,017
Effective Income Tax Rate Reconciliation, Percent
Statutory rate	21.00%	21.00%	21.00%
Foreign tax rate differential	0.50%	0.50%	(0.60%)
State income taxes, net of federal benefit	7.20%	0.30%	2.80%
Non-deductible expenses	1.30%	1.20%	(0.90%)
Tax benefits related to disposition of the Test and Inspection Services business	(116.40%)	0.00%	0.00%
Global intangible low-taxed income, net of tax credits	4.40%	0.60%	(0.70%)
Income tax credits	(9.70%)	(0.50%)	2.60%
Nondeductible executive compensation	0.90%	1.00%	(1.40%)
Tax on unremitted foreign earnings	1.20%	0.90%	(0.60%)
Change in valuation allowance	5.20%	(124.10%)	(46.40%)
Other	(0.30%)	0.40%	(0.30%)
Total income tax expense/ Effective rate	(84.70%)	(98.70%)	(24.50%)

Effective Income Tax Rate Reconciliation, Global Intangible Low-Taxed Income

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