Note 9 - Postretirement and Postemployment Benefits - Assumptions (Details) - Other Postretirement Benefits Plan [Member]	12 Months Ended
	Sep. 26, 2021	Sep. 27, 2020	Sep. 29, 2019
Discount rate	2.60%	2.70%
Expected long-term return on plan assets	4.00%	4.50%
Discount rate - service cost	2.50%	3.40%	4.00%
Discount rate - interest cost	1.90%	2.80%	3.70%
Expected long-term return on plan assets	4.00%	4.50%	4.50%