Retirement Plans, Weighted Average Assumptions Used to Determine Benefit Obligation and Benefit Cost (Details)	12 Months Ended
	Sep. 30, 2017	Oct. 01, 2016
Health-Care-Cost Trend Rates [Abstract]
Assumed health-care-cost trend rate	7.00%
Defined Benefit Pension Plans [Member]
Weighted-Average Assumptions [Abstract]
Discount rate for benefit obligation	3.50%	2.70%
Discount rate for net benefit cost	3.20%	3.50%
Expected return on plan assets for net benefit costs	6.40%	5.30%
Retiree Health Plan [Member]
Weighted-Average Assumptions [Abstract]
Discount rate for benefit obligation	3.30%	2.90%
Discount rate for net benefit cost	2.90%	3.50%
Expected return on plan assets for net benefit costs	0.00%	0.00%