PA Consulting Redeemable Noncontrolling Interests - Narrative (Details) - USD ($)	3 Months Ended		12 Months Ended
	Sep. 26, 2025	Sep. 27, 2024	Sep. 26, 2025	Sep. 27, 2024	Sep. 29, 2023	Mar. 02, 2021
Business Combination [Line Items]
Repurchase of redeemable noncontrolling interests			$ 10,449,000	$ 55,344,000	$ 92,939,000
Proceeds from issuances of redeemable noncontrolling interests			0	19,761,000	34,016,000
Temporary equity, fair value adjustment of redeemable noncontrolling interest			$ 0.0	(0.10)
Preference share effect on basic earnings per share (in dollars per share)	$ 0.01	$ 0.02
Award vesting percentage			40.00%
Fair value of awards not yet recognized	$ 142,100,000		$ 142,100,000
Fair value of such grants anticipated to vest			60.00%
PA Consulting Group Limited
Business Combination [Line Items]
Allocated share-based compensation expense			$ 75,300,000	13,400,000
Cash in employee benefit trust	1,400,000	$ 2,100,000	1,400,000	2,100,000
Equity Based Incentive Grants
Business Combination [Line Items]
Accrued cumulative expense associated with the vested grants	$ 103,800,000	$ 28,400,000	$ 103,800,000	28,400,000
PA Consulting Employees
Business Combination [Line Items]
Proceeds from issuances of redeemable noncontrolling interests				$ 19,800,000	$ 34,000,000
Ownership interest of employees	71.00%	70.00%	71.00%	70.00%		35.00%