Related Party Transactions (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 30, 2025	Mar. 31, 2024	Mar. 30, 2025	Mar. 31, 2024	Sep. 29, 2024
Related Party Transaction [Line Items]
Revenue	$ 1,322,113	$ 1,251,616	$ 2,742,674	$ 2,479,883
Reimbursable costs	14,575	13,115	29,356	30,738
Accounts receivable, net	1,223,214		1,223,214		$ 1,051,461
Contract assets	134,106		134,106		129,678
Contract liabilities	(373,591)		(373,591)		(351,738)
Related Party
Related Party Transaction [Line Items]
Revenue	16,017	$ 14,436	32,497	$ 33,404
Accounts receivable, net	13,677		13,677		15,612
Contract assets	939		939		1,625
Contract liabilities	$ (6,138)		$ (6,138)		$ (4,237)