Note 7 - Pension Plans - Net Periodic Cost (Benefit) (Details) - Pension Plan [Member] - USD ($) $ in Thousands	12 Months Ended
	Sep. 27, 2020	Sep. 29, 2019	Sep. 30, 2018
Service cost for benefits earned during the year	$ 1,361	$ 36	$ 48
Interest cost on projected benefit obligation	7,577	6,563	5,754
Expected return on plan assets	(12,986)	(8,073)	(7,933)
Amortization of net loss	3,166	1,135	2,025
Amortization of prior service benefit	(6)	(100)	(136)
Net periodic pension cost (benefit)	$ (888)	$ (439)	$ (242)