Summary of Significant Accounting Policies - Revenue by Contract Type (Details)	3 Months Ended		6 Months Ended
	Jul. 02, 2021	Jun. 26, 2020	Jul. 02, 2021	Jun. 26, 2020
Schedule Of Revenue By Contract Type [Line Items]
Revenue percent	100.00%	100.00%	100.00%	100.00%
Time-and-material [Member]
Schedule Of Revenue By Contract Type [Line Items]
Revenue percent	79.20%	78.90%	79.30%	80.50%
Progress Billing [Member]
Schedule Of Revenue By Contract Type [Line Items]
Revenue percent	18.70%	16.20%	18.40%	15.10%
Percentage-of-completion [Member]
Schedule Of Revenue By Contract Type [Line Items]
Revenue percent	2.10%	4.90%	2.30%	4.40%