Employee Benefit Plans - Components of Net Periodic Benefit Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2023	Sep. 24, 2022	Sep. 25, 2021
Components of net periodic benefit costs included in operating expenses [Abstract]
Settlement charge	$ 0	$ 840	$ 958
Pension Benefits [Member]
Components of net periodic benefit costs included in operating expenses [Abstract]
Interest cost	3,306	2,459	2,263
Expected return on plan assets	(1,355)	(1,392)	(1,266)
Amortization of prior service credit	0	0	0
Settlement charge	0	840	958
Recognized net actuarial loss (gain)	1,927	2,467	3,289
Net periodic benefit costs	3,878	4,374	5,244
Retiree Health and Life Benefits [Member]
Components of net periodic benefit costs included in operating expenses [Abstract]
Interest cost	166	81	77
Expected return on plan assets	0	0	0
Amortization of prior service credit	(498)	(498)	(498)
Settlement charge	0	0	0
Recognized net actuarial loss (gain)	(775)	(725)	(723)
Net periodic benefit costs	$ (1,107)	$ (1,142)	$ (1,144)