Description of Business and Basis of Presentation - Schedule of Revenues Realized from Each of These Types of Contracts (Details)	12 Months Ended
	Sep. 26, 2025	Sep. 27, 2024	Sep. 29, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Cost-reimbursable	68.00%	69.00%	70.00%
Fixed-price	32.00%	31.00%	30.00%