Income Taxes - Schedule of Income Tax Expense in Consolidated Statements of Earnings (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 26, 2025	Sep. 27, 2024	Sep. 29, 2023
Income Tax Disclosure [Abstract]
Statutory amount	$ 114,130	$ 163,230	$ 109,405
State taxes, net of the federal benefit	15,852	21,615	13,938
Exclusion of tax on non-controlling interests	(880)	(5,230)	(5,461)
Foreign:
Difference in tax rates of foreign operations	11,458	17,891	4,583
Expense/(Benefit) from foreign valuation allowance change	415	(27,780)	(1,305)
U.S. tax cost of foreign operations	76,014	72,887	68,662
Derecognition of deferred tax liabilities related to investment in Australian partnership	0	(61,614)	0
Other Includable Income	1,344	25,952	0
Tax differential on foreign earnings	89,231	27,336	71,940
Foreign tax credits	(48,885)	(33,402)	(36,180)
Tax Rate Change	98	(147)	(9,913)
Valuation allowance	988	12,339	(7,169)
Uncertain tax positions	11,153	(1,153)	(38,844)
Other items:
Disallowed officer compensation	5,157	5,394	7,081
Research and Development Credit	(35,637)	(17,110)	(2,133)
Stock compensation	18,376	3,296	162
Transaction Costs	675	8,500	4
Non-taxable mark-to-market Adjustment for Amentum investment	51,989	(39,255)	0
Other items – net	(6,692)	(13,920)	(1,494)
Total other items	33,868	(53,095)	3,620
Consolidated income tax expense from continuing operations	$ 215,555	$ 131,493	$ 101,336
Statutory tax rate	21.00%	21.00%	21.00%
State taxes, net of the federal benefit	2.90%	2.80%	2.70%
Exclusion of tax on non-controlling interests	(0.20%)	(0.70%)	(1.00%)
Foreign:
Difference in tax rates of foreign operations	2.10%	2.30%	0.90%
Expense/(Benefit) from foreign valuation allowance change	0.10%	(3.60%)	(0.30%)
U.S. tax cost of foreign operations	14.00%	9.40%	13.20%
Derecognition of deferred tax liabilities related to investment in Australian partnership	0.00%	(7.90%)	0.00%
Other Includable Income	0.20%	3.30%	0.00%
Tax differential on foreign earnings	16.40%	3.50%	13.80%
Foreign tax credits	(9.00%)	(4.30%)	(6.90%)
Tax Rate Change	0.00%	0.00%	(1.90%)
Valuation allowance	0.20%	1.60%	(1.40%)
Uncertain tax positions	2.10%	(0.10%)	(7.50%)
Other items:
Disallowed officer compensation	0.90%	0.70%	1.40%
Research and Development Credit	(6.60%)	(2.20%)	(0.40%)
Stock compensation	3.40%	0.40%	0.00%
Transaction Costs	0.10%	1.10%	0.00%
Non-taxable mark-to-market Adjustment for Amentum investment	9.60%	(5.10%)	0.00%
Other items – net	(1.20%)	(1.80%)	(0.30%)
Total other items	6.20%	(6.80%)	0.70%
Income taxes from continuing operations (percent)	39.70%	16.90%	19.50%