Revenue Recognition - Summary of Revenues (Detail) - Sales Revenue, Net [Member] - Revenue from Rights Concentration Risk [Member]	3 Months Ended
	Apr. 04, 2025	Mar. 29, 2024
Time And Materials Contracts [Member]
Disaggregation Of Revenue [Line Items]
Concentration Risk, Percentage	82.00%	80.00%
Time And Materials Contracts [Member] | Engineering and Other Scientific [Member]
Disaggregation Of Revenue [Line Items]
Concentration Risk, Percentage	66.00%	64.00%
Time And Materials Contracts [Member] | Environmental and Health [Member]
Disaggregation Of Revenue [Line Items]
Concentration Risk, Percentage	16.00%	16.00%
Fixed Price Contracts [Member]
Disaggregation Of Revenue [Line Items]
Concentration Risk, Percentage	18.00%	20.00%
Fixed Price Contracts [Member] | Engineering and Other Scientific [Member]
Disaggregation Of Revenue [Line Items]
Concentration Risk, Percentage	17.00%	19.00%
Fixed Price Contracts [Member] | Environmental and Health [Member]
Disaggregation Of Revenue [Line Items]
Concentration Risk, Percentage	1.00%	1.00%