Pension and Other Postretirement Benefit Plans - Summary of Changes in the Fair Value of Plans' Level 3 Assets (Details) - Pension Plan - Non-U.S. Plans - USD ($) $ in Thousands	12 Months Ended
Oct. 01, 2021	Oct. 02, 2020
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at the beginning of the year	$ 2,043,356	$ 1,916,637
Effect of exchange rate changes	(89,051)	(101,316)
Fair value of plan assets at the end of the year	2,203,495	2,043,356
Level 3
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at the beginning of the year	344,861
Fair value of plan assets at the end of the year	482,057	344,861
Real estate investments
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at the beginning of the year	115,805
Fair value of plan assets at the end of the year	187,689	115,805
Real estate investments \| Level 3
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at the beginning of the year	105,422	97,539
Purchases, sales, and settlements	6,288	(475)
Realized and unrealized gains (losses)	398	3,337
Acquisition of PA Consulting Plans, net of post-deal transfers	0
Effect of exchange rate changes	4,828	5,021
Fair value of plan assets at the end of the year	116,936	105,422
Insurance contracts
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at the beginning of the year	90,020
Fair value of plan assets at the end of the year	133,802	90,020
Insurance contracts \| Level 3
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at the beginning of the year	67,709	72,788
Purchases, sales, and settlements	2,413	(7,375)
Realized and unrealized gains (losses)	1,448	(1,399)
Acquisition of PA Consulting Plans, net of post-deal transfers	60,160
Effect of exchange rate changes	2,072	3,695
Fair value of plan assets at the end of the year	133,802	67,709
Hedge funds
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at the beginning of the year	178,883
Fair value of plan assets at the end of the year	247,339	178,883
Hedge funds \| Level 3
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at the beginning of the year	171,730	130,200
Purchases, sales, and settlements	51,513	29,999
Realized and unrealized gains (losses)	864	5,435
Acquisition of PA Consulting Plans, net of post-deal transfers	0
Effect of exchange rate changes	7,212	6,096
Fair value of plan assets at the end of the year	$ 231,319	$ 171,730

Defined Benefit Plan, Plan Assets Level 3 Reconciliation, Increase for Acquisition

No definition available.

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- Definition

Amount, measured using unobservable inputs, of increase (decrease) in plan assets of defined benefit plan from actual return (loss) on assets still held.

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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- Definition

Amount of asset segregated and restricted to provide benefit under defined benefit plan. Asset includes, but is not limited to, stock, bond, other investment, earning from investment, and contribution by employer and employee.

+ References

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- Definition

Amount of foreign currency translation gain (loss) which increases (decreases) plan assets of defined benefit plan.

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- Definition

Amount, measured using unobservable input, of increase (decrease) in plan asset of defined benefit plan from purchase, sale and settlement of trade associated with underlying investment.

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