PA Consulting Redeemable Noncontrolling Interests - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended
	Jun. 27, 2025	Jun. 28, 2024	Sep. 27, 2024
Business Combination [Line Items]
Repurchase of redeemable noncontrolling interests	$ 8,472	$ 41,788
Proceeds from issuances of redeemable noncontrolling interests	$ 0	$ 19,761
Preference share effect on basic earnings per share (in dollars per share)	$ 0.10	$ 0.01
PA Consulting Group Limited
Business Combination [Line Items]
Cash in employee benefit trust	$ 2,700		$ 2,100
Equity-Based Incentive Grants
Business Combination [Line Items]
Accrued cumulative expense associated with the vested grants	50,600		$ 28,400
Allocated share-based compensation expense	$ 20,600	$ 11,500
Share-Based Payment Arrangement, Tranche One | Equity-Based Incentive Grants
Business Combination [Line Items]
Award vesting percentage	40.00%
Share-Based Payment Arrangement, Tranche Two | Equity-Based Incentive Grants
Business Combination [Line Items]
Award vesting percentage	60.00%
PA Consulting Employees
Business Combination [Line Items]
Ownership interest of employees	71.00%		70.00%