Postretirement and Postemployment Benefits - Narrative (Details) $ in Thousands	12 Months Ended
	Sep. 24, 2023 USD ($)	Sep. 25, 2022 USD ($)	Sep. 26, 2021 USD ($)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Amortization of prior service cost (credit) expected to be recognized during the next fiscal year	$ 800
Other Postretirement Benefits Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net actuarial gain expected to be recognized in net periodic pension cost during next fiscal year	1,200
Amortization of prior service cost (credit) expected to be recognized during the next fiscal year	$ 400
Assumptions used calculating net periodic benefit cost, expected long-term rate of return on plan assets	5.00%	5.00%	4.00%
Non-current assets	$ 21,565	$ 19,066
Expected future employer contributions, next fiscal year	0
Postemployment benefit obligation	11,252	12,287	$ 18,538
Other Postretirement Benefits Plan | U.S. Small Cap Value Equity Common/Collective Fund
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Investment in equity securities measured at fair value, recognized in net income	900	800
Other Postretirement Benefits Plan | Global Equity Long/Short Common/Collective Hedge Fund-of-funds
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Investment in equity securities measured at fair value, recognized in net income	$ 3,000	2,800
Maximum percentage of equity investment redeemable	0.90
Other Postretirement Benefits Plan | Global Equity Long/Short Common/Collective Hedge Fund-of-funds | Minimum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Notice for redemption of equity investment	90 days
Other Postretirement Benefits Plan | Global Equity Long/Short Common/Collective Hedge Fund-of-funds | Maximum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Notice for redemption of equity investment	120 days
Other Postretirement Benefits Plan | Level 3
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Purchases, sales or transfers of assets classified as level 3	$ 0	0
Postemployment Retirement Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Curtailment gain	0	0	23,830
Liability (gain)/loss due to curtailment			$ 23,800
Postemployment benefit obligation	1,600	1,800
Retiree Medical Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Non-current assets	$ 400	$ 600