PA Consulting Business Combination - Change in Redeemable Noncontrolling Interest (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 30, 2022	Dec. 31, 2021
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Noncontrolling interest, Beginning balance	$ 44,336
Attribution of Preferred Dividend to Common Shareholders	(1,873)	$ (14,049)
Noncontrolling interest, Ending balance	49,494
PA Consulting Employees
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Noncontrolling interest, Beginning balance	632,522
Accrued Preferred Dividend to Preference Shareholders	16,290
Attribution of Preferred Dividend to Common Shareholders	(16,290)
Net earnings attributable to redeemable noncontrolling interests to Common Shareholders	3,992
Redeemable Noncontrolling interests redemption value adjustment	23,317
Repurchase of redeemable noncontrolling interests	(69,690)
Cumulative translation adjustment and other	37,768
Noncontrolling interest, Ending balance	$ 627,909