Segment Information (Detail) - USD ($) $ in Thousands	3 Months Ended
Apr. 03, 2020	Mar. 29, 2019
Segment Reporting Information [Line Items]
Revenues	$ 105,953	$ 99,031
Operating Income	35,988	15,754
Capital Expenditures	1,039	6,341
Depreciation and Amortization	1,786	1,590
Operating segments
Segment Reporting Information [Line Items]
Operating Income	33,894	32,170
Capital Expenditures	628	1,821
Depreciation and Amortization	1,184	1,166
Corporate
Segment Reporting Information [Line Items]
Operating Income	2,094	(16,416)
Capital Expenditures	411	4,520
Depreciation and Amortization	602	424
Engineering and Other Scientific \| Operating segments
Segment Reporting Information [Line Items]
Revenues	84,887	80,254
Operating Income	26,641	25,974
Capital Expenditures	566	1,778
Depreciation and Amortization	1,137	1,121
Environmental and Health \| Operating segments
Segment Reporting Information [Line Items]
Revenues	21,066	18,777
Operating Income	7,253	6,196
Capital Expenditures	62	43
Depreciation and Amortization	$ 47	$ 45

The current period expense charged against earnings on long-lived, physical assets not used in production, and which are not intended for resale, to allocate or recognize the cost of such assets over their useful lives; or to record the reduction in book value of an intangible asset over the benefit period of such asset; or to reflect consumption during the period of an asset that is not used in production.

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