Related Party Transactions (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 29, 2025	Jun. 30, 2024	Jun. 29, 2025	Jun. 30, 2024	Sep. 29, 2024
Related Party Transaction [Line Items]
Revenue	$ 1,369,816	$ 1,344,323	$ 4,112,490	$ 3,824,205
Reimbursable costs	14,222	15,287	43,578	46,025
Accounts receivable, net	1,127,519		1,127,519		$ 1,051,461
Contract assets	142,852		142,852		129,678
Contract liabilities	(389,856)		(389,856)		(351,738)
Related Party
Related Party Transaction [Line Items]
Revenue	16,267	$ 16,753	48,764	$ 50,157
Accounts receivable, net	13,368		13,368		15,612
Contract assets	1,184		1,184		1,625
Contract liabilities	$ (5,511)		$ (5,511)		$ (4,237)