CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Sep. 26, 2020	Sep. 28, 2019	Sep. 29, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 60,758	$ 68,632	$ 76,534
Other comprehensive (loss) income:
Amortization of net actuarial losses and prior service credits into earnings and net change in funded status of benefit plans	(641)	(1,516)	4,142
Recognition in earnings of net actuarial loss for pension settlement	1,051	0	0
Other comprehensive income (loss)	410	(1,516)	4,142
Total comprehensive income	$ 61,168	$ 67,116	$ 80,676