Joint Ventures and VIE's and Other Investments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Apr. 01, 2022	Apr. 02, 2021	Apr. 01, 2022	Apr. 02, 2021	Oct. 01, 2021	Mar. 02, 2021
Variable Interest Entity [Line Items]
Consolidated assets	$ 15,183,292		$ 15,183,292		$ 14,632,609
Amount by which equity method investments exceeded share of venture net assets	36,300		36,300
Income from equity method investments			(13,280)	$ (6,353)
Impairment of long-lived assets and equity method investment			74,585	33,197
PA Consulting Employees
Variable Interest Entity [Line Items]
Ownership interest of employees						35.00%
PA Consulting Group Limited
Variable Interest Entity [Line Items]
Percentage of outstanding shares of common and preferred stock acquired						65.00%
AWE Management Ltd
Variable Interest Entity [Line Items]
Percentage of ownership interest in joint venture					24.50%
Impairment of long-lived assets and equity method investment		$ 33,200		33,200
C3
Variable Interest Entity [Line Items]
Gain on sale of stock			(48,600)
Consolidated Joint Venture | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Consolidated assets	386,900		386,900		$ 289,800
Consolidated liabilities	255,800		255,800		220,800
Unconsolidated Joint Venture | VIE, not primary beneficiary
Variable Interest Entity [Line Items]
Consolidated assets	119,500		119,500		115,100
Consolidated liabilities	146,100		146,100		129,500
Equity method investments	105,400		105,400		121,300
Income from equity method investments	12,500	$ 11,900	19,300	$ 30,200
Accounts receivable from unconsolidated joint ventures accounted for under the equity method	$ 22,400		$ 22,400		$ 19,700