Note 6 - Pension, Postretirement and Postemployment Defined Benefit Plans - Net Period Postretirement Cost (Benefit) Components for Postretirement Plans (Details) - USD ($)	3 Months Ended		9 Months Ended
	Jun. 30, 2019	Jun. 24, 2018	Jun. 30, 2019	Jun. 24, 2018
Pension Plan [Member]
Service cost for benefits earned during the period	$ 9,000	$ 12,000	$ 27,000	$ 36,000
Interest cost on projected benefit obligation	1,641,000	1,438,000	4,923,000	4,314,000
Expected return on plan assets	(2,018,000)	(1,983,000)	(6,055,000)	(5,949,000)
Amortization of net loss	284,000	506,000	851,000	1,518,000
Amortization of prior service benefit	(25,000)	(34,000)	(75,000)	(102,000)
Pension benefit	(109,000)	(61,000)	(329,000)	(183,000)
Curtailment gains		(2,031,000)
Postretirement Health Coverage [Member]
Interest cost on projected benefit obligation	103,000	90,000	309,000	271,000
Expected return on plan assets	(270,000)	(270,000)	(811,000)	(810,000)
Amortization of net loss	(244,000)	(246,000)	(732,000)	(738,000)
Amortization of prior service benefit	(181,000)	(196,000)	(543,000)	(588,000)
Pension benefit	(592,000)	(622,000)	(1,777,000)	(3,896,000)
Curtailment gains				$ (2,031,000)