Note 6 - Pension, Postretirement and Postemployment Defined Benefit Plans (Details Textual) - USD ($)	3 Months Ended			6 Months Ended		12 Months Ended
	Mar. 27, 2022	Dec. 26, 2021	Mar. 28, 2021	Mar. 27, 2022	Mar. 28, 2021	Sep. 26, 2021
Multiemployer Plans, Withdrawal Obligation	$ 25,253,000			$ 25,253,000		$ 23,471,000
Multiemployer Plans, Withdrawal Obligation, Period (Year)	20 years
Postemployment Retirement Benefits [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Curtailment		$ 1,027,000				23,830,000
Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Curtailment		(6,507,000)				23,830,000
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Curtailment		$ 1,027,000				$ 23,830,000
Pension Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Curtailment	$ (0)		$ (0)	1,027,000	$ (0)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Curtailment	(0)		$ (0)	1,027,000	(0)
Defined Benefit Plan, Plan Assets, Contributions by Employer				0	$ 965,000
Defined Benefit Plan, Expected Future Employer Contributions, Remainder of Fiscal Year	$ 0			$ 0