REVENUE - Revenue by Contract Type (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Oct. 02, 2026	Sep. 26, 2025	Oct. 02, 2026	Sep. 26, 2025
Disaggregation of Revenue [Line Items]
Total revenue	$ 1,271,463	$ 1,167,137	$ 3,782,234	$ 3,261,390
Cost-plus and cost-reimbursable
Disaggregation of Revenue [Line Items]
Total revenue	$ 692,452	702,557	$ 2,180,075	1,973,210
Revenue, percent change	(1.40%)		10.50%
Firm-fixed-price
Disaggregation of Revenue [Line Items]
Total revenue	$ 419,111	436,528	$ 1,181,520	1,205,705
Revenue, percent change	(4.00%)		(2.00%)
Time-and-materials
Disaggregation of Revenue [Line Items]
Total revenue	$ 159,900	$ 28,052	$ 420,639	$ 82,475
Revenue, percent change	470.00%		410.00%

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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+ Details

- Definition

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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