Employee Benefit Plans - Schedule of Assumptions Used (Details)	12 Months Ended
Sep. 26, 2020	Sep. 28, 2019	Sep. 29, 2018
Pension Benefits [Member]
Actuarial assumptions [Abstract]
Weighted-average discount rate used in calculating benefit obligations	2.125%	2.875%
Average rate of compensation increase	0.00%	0.00%
Health care cost trend	0.00%	0.00%
Assumptions used in calculating benefit cost [Abstract]
Weighted-average discount rate	2.875%	4.00%	3.50%
Average rate of compensation increase	0.00%	0.00%	0.00%
Weighted-average expected long-term rate of return on plan assets	1.80%	2.55%	2.50%
Health care cost trend	0.00%	0.00%	0.00%
Retiree Health and Life Benefits [Member]
Actuarial assumptions [Abstract]
Weighted-average discount rate used in calculating benefit obligations	1.375%	2.375%
Average rate of compensation increase	0.00%	0.00%
Health care cost trend	5.72%	6.01%
Assumptions used in calculating benefit cost [Abstract]
Weighted-average discount rate	2.375%	3.75%	3.00%
Average rate of compensation increase	0.00%	0.00%	0.00%
Weighted-average expected long-term rate of return on plan assets	0.00%	0.00%	0.00%
Health care cost trend	6.01%	6.29%	6.57%

Weighted average rate for present value of future retirement benefits cash flows, used to determine benefit obligation of defined benefit plan.

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- Definition

Weighted average rate increase of compensation, used to determine benefit obligation of defined benefit plan. Plan includes, but is not limited to, pay-related defined benefit plan.

+ References

+ Details

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- Definition

Weighted average rate for present value of future retirement benefits cash flows, used to determine net periodic benefit cost of defined benefit plan.

+ References

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- Definition

Weighted average rate of return on plan assets, reflecting average rate of earnings expected on existing plan assets and expected contributions, used to determine net periodic benefit cost of defined benefit plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (k)(3)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e2919-114920

+ Details

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- Definition

Weighted average rate of compensation increase used to determine net periodic benefit cost of defined benefit plan. Plan includes, but is not limited to, pay-related defined benefit plan.

+ References

+ Details

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- Definition

Assumed rate, for next fiscal year, based on annual change in cost of health care cost benefits used to measure expected cost of benefits covered by defined benefit postretirement plan. Factors include, but are not limited to, estimate of health care inflation, change in health care utilization or delivery pattern, technological advances, and change in health status of participant. Excludes factors for change in composition of plan population by age and dependency status.

+ References

+ Details

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- Definition

Ultimate trend rate for health care cost for defined benefit postretirement plan.

+ References

+ Details

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- References

No definition available.

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- References

No definition available.

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